Posts Tagged ‘Tactical Ventilation’

The sixth tactical implication identified in the Underwriters Laboratories study of the Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction (Kerber, 2011) identifies potential hazards and risks related to the tactic of Vent Enter Search (VES).

Kerber (2011) provides a straightforward explanation of this tactic.

It can be described as ventilating a window, entering through the window, searching that room and exiting out the same window entered…A primary of objective of VES is to close the door of the room ventilated to isolate the flow path…

Origins and Context

While it is difficult to identify or isolate the origins of many fireground tactics, VES has been practiced by FDNY for many years and is described in detail in the Firefighting Procedures Volume 3, Book 4: Ladder Company Operations at Private Dwellings manual (FDNY, 1997). As described in Ladder Company Operations at Private Dwellings, FDNY truck companies are staffed with an officer, apparatus operator, and four firefighters and are divided into two teams; inside team and outside team. While tactics are dependent on the type of structure and fire conditions; VES is performed by the outside team while the inside team works in conjunction with an engine company, supporting fire attack and searching from the interior. In this context, VES is part of a coordinated tactical operation.

It is also important to recognize the impact of changes in the fire environment since the development of this tactic (likely in the 1960s). Changes in the speed of fire development are graphically illustrated in the Underwriters Laboratories (UL) test of fire development with modern and legacy furnishings.

The tremendous fuel load, development of ventilation limited conditions, and rapid transition from tenable to untenable conditions for firefighters following increased ventilation (without initiation of fire control), reduce the time for Firefighters to make entry and control the door when performing VES in the modern fire environment.

Influence on Fire Behavior

The following incident illustrates the rapid changes in conditions that can result during VES operations. This information was originally presented in the post titled Criticism Versus Critical Thinking. This incident involved VES at a residential structure where rapid fire progress required the Captain conducting the search to perform emergency window egress from a second floor window onto a ladder.

Companies were dispatched to a residential fire at 0400 hours with persons reported. On arrival, cars were observed in the driveway and neighbors reported the likely location of a trapped occupant on the second floor.

Given fire conditions on Floor 1, the Captain of the first in truck, a 23 year veteran, determined that Vent, Enter, and Search (VES) was the best option to quickly search and effect a rescue.

The following video clip illustrates conditions encountered at this residential fire:

Find more videos like this on firevideo.net

In his, vententersearch.com post Captain Van Sant provided the following information about his observations and actions:

When we vent[ed] the window with the ladder, it looks like the room is burning, but the flames you see are coming from the hallway, and entering through the top of the bedroom doorway. Watch it again and you’ll see the fire keeps rolling in and across the ceiling.

When I get to the window sill, the queen-sized bed is directly against the window wall, so there is no way to “check the floor” … Notice that you continue to see my feet going in, because I’m on the bed.

Believe me, in the beginning, this was a tenable room both for me and for any victim that would have been in there…

My goal was to get to the door and close it, just like VES is supposed to be done. We do it successfully all the time.

When I reached the other side of the bed, I dropped to the floor and began trying to close the door. Unfortunately, due to debris on the floor, the door would not close [emphasis added].

Conditions were still quite tenable at this point, but I knew with the amount of fire entering at the upper level, and smoke conditions changing, things were going to go south fast…

I kept my eyes on my exit point, and finished my search, including the closet, which had no doors on it. Just as I was a few feet from the window, the room lit off…

Tactical Considerations

Is VES an appropriate tactic for primary search in private dwellings? This question must be placed into operational context bounded by fire dynamics, resources and staffing, experience level of the firefighters involved, potential for survivable occupants, and the fireground risk management philosophy of the department. Consider the following:

• There have been instances where VES has resulted in saving of civilian life.
• There have been instances where VES has resulted in significant thermal injury to firefighters.
• The UL ventilation tests (Kerber, 2011) demonstrate that conditions rapidly become untenable for civilian occupants in rooms with open doors. Rooms with closed doors remain tenable for civilian occupants for a considerable time.
• VES may result in rapid search of specific threatened areas.
• VES is a high risk tactic that involves working alone (but if a second firefighter remains at the entry point this is similar to oriented search).
• VES (as normally practiced) involves working without a hoseline.
• VES changes the ventilation profile and places firefighters in the flow path between the fire and an exhaust opening (unless or until the door to the compartment is closed)
• As demonstrated in the UL ventilation tests (Kerber, 2011), thermal conditions change from a tenable operating environment for firefighters to untenable and life threatening in a matter of seconds.

Based on these factors, you may determine that VES is not an appropriate tactic for primary search under any circumstances, or you may determine that it might be appropriate under specific circumstances. The following tactical scenarios may provide a framework for discussion of these issues.

Scenario 1:You have responded to a fire in a medium sized, two-story, wood frame, single-family dwelling at 02:13 hours. You observe a smoke issuing at moderate velocity from the eaves and condensed pyrolizate on the inside of window glazing. A dull reddish glow can be observed through several adjacent windows on the Charlie Side (back of the house), Floor 1.

Given your normal first alarm assignment and staffing Is VES an appropriate option for primary search given the conditions described and potential for possible occupants? Why or why not?

Scenario 2: You have the same building, smoke, air track, heat, and flame indicators as in Scenario 1, but a female occupant meets you on arrival and reports that her husband is trying to rescue their daughter who was sleeping in a bedroom on Floor 2 at the Alpha/Bravo corner of the house.

Given your normal first alarm assignment and staffing Is VES an appropriate option for primary search given the conditions described and reported occupants?  Why or why not?

Scenario 3: You have the same building, smoke, air track, heat, and flame indicators as in Scenario 1, and observe two occupants, an adult male and a female child in a window on Floor 2 at the Alpha/Bravo corner of the house. Smoke at low velocity is issuing from the open window above the occupants. However, before you can raise a ladder to rescue the occupants in the window, they disappear from view and the volume and velocity of smoke discharge from the window increases.

Given your normal first alarm assignment and staffing Is VES an appropriate option for primary search given the conditions described and initial observation of occupants? Why or why not?

Vertical Ventilation Study

UL has commenced a study on the Effectiveness of Vertical Ventilation and Fire Suppression Tactics using the same legacy and contemporary residential structures used in their study of horizontal ventilation. This research project will examine a range of vertical ventilation variables including the size, location, and timing of openings. In addition, further research will be conducted on the effectiveness of exterior streams and their impact on interior conditions.

Preliminary design parameters for the study were developed in conjunction with a technical panel representing a wide range of jurisdictions and types of fire service agencies, including:

• Atlanta Fire Department (GA)
• Central Whidbey Island Fire & Rescue (WA)
• Chicago Fire Department (IL)
• Cleveland Fire Department (OH)
• Coronado Fire Department (CA)
• Fire Department of the City of New York (FDNY) (NY)
• Loveland-Symmes Fire Department (OH)
• National Institute of Standards and Technology (NIST) (MD)
• Northbrook Fire Department (IL)
• Milwaukee Fire Department (WI)
• Lake Forest Fire Department (IL)
• Phoenix Fire Department (AZ)

Full scale tests are anticipated to begin in January 2012. I will provide updates as this research project progresses.

References

Fire Department of the City of New York (FDNY). (1997) Firefighting prodedures volume 3 book 4: Ladder company operations at private dwellings. New York: Author.

Kerber, S. (2011). Impact of ventilation on fire behavior in legacy and contemporary residential construction. Retrieved July 16, 2011 from http://www.ul.com/global/documents/offerings/industries/buildingmaterials/fireservice/ventilation/DHS%202008%20Grant%20Report%20Final.pdf

The fifth tactical implication identified in the Underwriters Laboratories study of the Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction (Kerber, 2011) is described as failure of the smoke layer to lift following horizontal natural ventilation and smoke tunneling and rapid air movement in through the front door.

In the experiments conducted by UL, both the single and two story dwellings filled rapidly with smoke with the smoke layer reaching the floor prior to ventilation. This resulted in zero visibility throughout the interior (with the exception of the one bedroom with a closed door). After ventilation, the smoke layer did not lift (as many firefighters might anticipate) as the rapid inward movement of air simply produced a tunnel of clear space just inside the doorway.

Put in the context of the Building, Smoke, Air Track, Heat, and Flame (B-SAHF) fire behavior indicators, these phenomena fit in the categories of smoke and air track. Why did these phenomena occur and what can firefighters infer based on observation of these fire behavior indicators?

Smoke Versus Air Track

There are a number of interrelationships between Smoke and Air Track. However, in the B-SAHF organizing scheme they are considered separately. As we begin to develop or refine the map of Smoke Indicators it is useful to revisit the difference between these two categories in the B-SAHF scheme.

Smoke: What does the smoke look like and where is it coming from? This indicator can be extremely useful in determining the location and extent of the fire. Smoke indicators may be visible on the exterior as well as inside the building. Don’t forget that size-up and dynamic risk assessment must continue after you have made entry!

Air Track: Related to smoke, air track is the movement of both smoke (generally out from the fire area) and air (generally in towards the fire area). Observation of air track starts from the exterior but becomes more critical when making entry. What does the air track look like at the door? Air track continues to be significant when you are working on the interior.

Smoke Indicators

There are a number of smoke characteristics and observations that provide important indications of current and potential fire behavior. These include:

• Location: Where can you see smoke (exterior and interior)?
• Optical Density (Thickness): How dense is the smoke? Can you see through it? Does it appear to have texture like velvet (indicating high particulate content)?
• Color: What color is the smoke? Don’t read too much into this, but consider color in context with the other indicators.
• Physical Density (Buoyancy): Is the smoke rising, sinking, or staying at the same level?
• Thickness of the Upper Layer: How thick is the upper layer (distance from the ceiling to the bottom of the hot gas layer)?

As discussed in Reading the Fire: Smoke Indicators Part 2, these indicators can be displayed in a concept map to show greater detail and their interrelationships (Figure 1).

Figure 1. Smoke Indicators Concept Map

Air Track

Air track includes factors related to the movement of smoke out of the compartment or building and the movement of air into the fire. Air track is caused by pressure differentials inside and outside the compartment and by gravity current (differences in density between the hot smoke and cooler air). Air track indicators include velocity, turbulence, direction, and movement of the hot gas layer.

• Direction: What direction is the smoke and air moving at specific openings? Is it moving in, out, both directions (bi-directional), or is it pulsing in and out?
• Wind: What is the wind direction and velocity? Wind is a critical indicator as it can mask other smoke and air track indicators as well as serving as a potentially hazardous influence on fire behavior (particularly when the fire is in a ventilation controlled burning regime).
• Velocity & Flow: High velocity, turbulent smoke discharge is indicative of high temperature. However, it is essential to consider the size of the opening as velocity is determined by the area of the discharge opening and the pressure. Velocity of air is also an important indicator. Under ventilation controlled conditions, rapid intake of air will be followed by a significant increase in heat release rate.

As discussed in Reading the Fire: Air Track Indicators Part 2, these indicators can be displayed in a concept map to show greater detail and their interrelationships (Figure 2).

Figure 2. Air Track Indicators Concept Map

air t

Discharge of smoke at openings and potential openings (Building Factors) is likely the most obvious indicator of air track while lack of smoke discharge may be a less obvious, but equally important sign of inward movement of air. Observation and interpretation of smoke and air movement at openings is an essential part of air track assessment, but it must not stop there. Movement of smoke and air on the interior can also provide important information regarding fire behavior.

An Ongoing Process

Reading the fire is an ongoing process, beginning with reading the buildings in your response area prior to the incident and continuing throughout firefighting operations. It is essential to not only recognize key indicators, but to also note changing conditions. This can be difficult when firefighters and officer are focused on the task at hand.

UL Experiment 13

This experiment examined the impact of horizontal ventilation through the door on Side A and one window as high as possible on Side C near the seat of the fire. The family room was the fire compartment. This room had a high (two-story) ceiling with windows at ground level and the second floor level (see Figure 3).

Figure 3. Two-Story Dwelling

In this experiment, the fire was allowed to progress for 10:00 after ignition, at which point the front door (see Figure 3) was opened to simulate firefighters making entry. Fifteen seconds after the front door was opened (10:15), an upper window in the family room (see Figure 3) was opened. No suppression action was taken until 12:28, at which point a 10 second application of water was made through the window on Side C using a straight stream from a combination nozzle.

As with all the other experiments in this series fire development followed a consistent path. The fire quickly consumed much of the available oxygen inside the building and became ventilation controlled. At oxygen concentration was reduced, heat release rate and temperature within the building also dropped. Concurrently, smoke and air track indicators visible from the exterior were diminished. Just prior to opening the door on Side A, there was little visible smoke from the structure (see Figure 4).

Figure 4. Experiment 13 at 00:09:56 (Prior to Ventilation)

As illustrated in Figure 5, a bi-directional air track was created when the front door was opened. Hot smoke flowed out the upper area of the doorway while air pushed in the bottom creating a tunnel of clear space inside the doorway (but no generalized lifting of the upper layer.

Figure 5. Experiment 13 at 00:10:14 (Door Open)

As illustrated in Figure 6, opening the upper level window in the family room resulted in a unidirectional air track flowing from the front door to the upper level window in the family room. No significant exhaust of smoke can be seen at the front door, while a large volume of smoke is exiting the window. However, while the tunneling effect at floor level was more pronounced (visibility extended from the front door to the family room), there was no generalized lifting of the upper layer throughout the remainder of the building.

Figure 6. Experiment 13 at 00:10:21 (Door and Window Open)

With the increased air flow provided by ventilation through the door on Side A and Window at the upper level on Side C, the fire quickly transitioned to a fully developed stage in the family room. The heat release rate (HRR) and smoke production quickly exceeded the limited ventilation provided by these two openings and the air track at the front door returned to bi-directional (smoke out at the upper level and air in at the lower level) as shown in Figure 7.

Figure 7. Experiment 13 at 00:11:22 (Door and Window Open)

What is the significance of this observation? Movement of smoke out the door (likely the entry point for firefighters entering for fire attack, search, and other interior operations) points to significant potential for flame spread through the upper layer towards this opening. The temperature of the upper layer is hot, but flame temperature is even higher, increasing the radiant heat flux (transfer) to crews working below. Flame spread towards the entry point also has the potential to trap, and injure firefighters working inside.

Gas Velocity and Air Track

A great deal can be learned by examining both the visual indicators illustrated in Figures 4-7 and measurements taken of gas velocity at the front door. During the ventilation experiments conducted by UL, gas velocities were measured at the front door and at the window used for ventilation (see Figure 3). Five bidirectional probes were placed in the doorway at 0.33 m (1’) intervals. Positive values show gas movement out of the building while negative values show inward gas movement. In order to provide a simplified view of gas movement at the doorway, Figure 8 illustrates gas velocity 0.33 m (1’) below the top of the door, 0.33 m (1’) from the bottom of the door, and 0.66 m (2’) above the bottom of the door.

A bidirectional (out at the top and in at the bottom) air track developed at the doorway before the door was opened (see Figure 8) as a result of leakage at this opening. It is interesting to note variations in the velocity of inward movement of air from the exterior of the building, likely a result of changes in combustion as the fire became ventilation controlled. The outward flow at the upper level resulted in visible smoke on the exterior of the building. While not visible, inward movement of air was also occurring (as shown by measurement of gas velocity at lower levels in the doorway.

Creation of the initial ventilation opening by opening the front door created a strong bidirectional air track with smoke pushing out the top of the door while air rapidly moved in the bottom. Had the door remained the only ventilation opening, this bidirectional flow would have been sustained (as it was in all experiments where the door was the only ventilation opening).

Opening the upper window in the family room resulted in a unidirectional flow inward through the doorway. However, this phenomenon was short lived, with the bidirectional flow reoccurring in less than 60 seconds. This change in air track resulted from increased heat release rate as additional air supply was provided to the fire in the family room.

Figure 8. Front Door Velocities

Note: Adapted from Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction (p. 243), by Stephen Kerber, Northbrook, IL: Underwriters Laboratories, 2011.

While not the central focus of the UL research, these experiments also examined the effects of exterior fire stream application on fire conditions and tenability. Each experiment included a 10 second application with a straight stream and a 10 second application of a 30^o fog pattern. Between these two applications, fire growth was allowed to resume for approximately 60 seconds.

The straight stream application resulted in a reduction of temperature in the fire compartment and adjacent compartments (where there was an opening to the family room or hallway) as water applied through the upper window on Side C (ventilation opening) cooled the compartment linings (ceiling and opposite wall) and water deflected off the ceiling dropped onto the burning fuel. As the stream was applied, air track at the door on Side A changed from bidirectional to unidirectional (inward). This is likely due to the reduction of heat release rate achieved by application of water onto the burning fuel with limited steam production.

When the fog pattern was applied, there was also a reduction of temperature in the fire compartment and adjacent compartments (where there was an opening in the family room or hallway) as water was applied through the upper window on Side C (ventilation opening) cooled the upper layer, compartment linings, and water deflected off the ceiling dropped onto the burning fuel. The only interconnected area that showed a brief increase in temperature was the ceiling level in the dining room. However, lower levels in this room showed an appreciable drop in temperature. Air track at the door on Side A changed from bidirectional to unidirectional (outward) when the fog stream was applied. This effect is likely due to air movement inward at the window on Side C and the larger volume of steam produced on contact with compartment linings as a result of the larger surface area of the fog stream.

The effect of exterior streams will be examined in more detail in a subsequent post.

Important Lessons

The fifth tactical implication identified in the Underwriters Laboratories study of the Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction (Kerber, 2011) is described as failure of the smoke layer to lift following horizontal natural ventilation and smoke tunneling and rapid air movement in through the front door.

Additional lessons that can be learned from this experiment include:

• Ventilating horizontally at a high point results in higher flow of both air and smoke.
• Increased inward air flow results in a rapid increase in heat release rate.
• The rate of fire growth quickly outpaced the capability of the desired exhaust opening, returning the intended inlet to a bi-directional air track (potentially placing firefighters entering for fire attack or search at risk due to rapid fire spread towards their entry point).

Tactical applications of this information include:

• Ensure that the attack team is in place with a charged line and ready to (or has already) attack the fire (not simply ready to enter the building) before initiating horizontal ventilation.
• Cool the upper layer any time that it is above 100^o C (212^o F) to reduce radiant and convective heat flux and to limit potential for ignition and flaming combustion in the upper layer.

Note that this research project did not examine the impact of gas cooling, but examination of the temperatures at the upper levels in this experiment (and others in this series) point to the need to cool hot gases overhead.

What’s Next?

I am on the hunt for videos that will allow readers to apply the tactical implications of the UL study that have been examined to this point in conjunction with the B-SAHF fire behavior indicators. My next post will likely provide an expanded series of exercises in Reading the Fire.

The next tactical implication identified in the UL study (Kerber, 2011) examines the hazards encountered during Vent Enter Search (VES) tactical operations. A subsequent post will examine this tactic in some detail and explore this tactical implication in greater depth.

References

Kerber, S. (2011). Impact of ventilation on fire behavior in legacy and contemporary residential construction. Retrieved July 16, 2011 from http://www.ul.com/global/documents/offerings/industries/buildingmaterials/fireservice/ventilation/DHS%202008%20Grant%20Report%20Final.pdf

The fourth tactical implication identified in the Underwriters Laboratories study of the Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction (Kerber, 2011) is that fire attack and (tactical) ventilation must be coordinated. This recommendation has been repeated in National Institute for Occupational Safety and Health (NIOSH) Death in the Line of Duty Reports for many years. In fact, most reports on firefighter fatalities related to rapid fire progression contain this recommendation.

Importance of Coordination

Coordination of (tactical) ventilation and fire attack as a tactical implication is closely related to the first two tactical implications identified in the UL study; potential changes in fire behavior based on stages of fire development, burning regime, and changes in ventilation profile that increase oxygen supplied to the fire.

If air is added to the fire and water is not applied in the appropriate time frame the fire gets larger and the hazards to firefighters increase. Examining the times to untenability provides the best case scenario of how coordinated the attack needs to be. Taking the average time for every experiment from the time of ventilation to the time of the onset of firefighter untenability conditions yields 100 seconds for the one-story house and 200 seconds for the two-story house. In many of the experiments from the onset of firefighter untenability until flashover was less than 10 seconds. These times should be treated as very conservative. If a vent location already exists because the homeowner left a window or door open then the fire is going to respond faster to additional ventilation openings because the temperatures in the house are going to be higher at the time of the additional openings (Kerber, 2011, p. 289-290)

The Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction Underwriters Laboratories (UL) on-line course and report provide an example of firefighters are at risk when ventilation is performed prior to entry, fire attack is delayed, and other tactical operations such as primary search are initiated.

In UL’s hypothetical example, the firefighters make entry into the one-story house, search the living room (fire compartment), the kitchen, and dining room shortly after forcing the door and ventilating a large window in the fire compartment. Consider a somewhat different scenario, with the same fire conditions.

Companies respond to a residential fire with persons reported during the early morning hours. A truck and engine arrive almost simultaneously and while the engine lays a supply line from a nearby hydrant, the truck company forces entry, ventilates a window on Side A, and begins primary search (anticipating that the engine crew will be right behind them to attack the fire). The engine completes a forward lay and begins to stretch an attack line after the search team has made entry.

Figure 1. Timeline and Progression of Primary Search

Figure 2. View of the Living Room (Fire Compartment) from the Door on Side A

As illustrated in Figure 3, visible flaming combustion when the door is opened at 08:00 is limited to a small flame from the top of the couch just inside the door on Side A. However, in the 30 seconds that it takes for the search team to make entry, flaming combustion has resumed and flames are near or at the ceiling above the couch. The search team may estimate that they have time to complete a quick search of the bedrooms (likely location of the reported persons). However, fire development progresses to untenable conditions within a minute, trapping the crew on Side D of the house.

Figure 3. Fire Progression in the Living Room 00:08:00 to 00:10:00

As the search team completes primary search of Bedroom 2 and moves towards Bedroom 3 in the hallway, conditions have deteriorated to an untenable level. Figure 4 illustrates the change in temperature at the 3’ level in the Living Room (fire compartment). Shortly before the search team reached Bedroom 2, fire conditions in the living room began to change dramatically, with temperature at the 3’ level transitioning from ordinary to extreme, quickly becoming untenable in the living room, hallway and adjacent compartments. In addition to this significant change in temperature, flames (with temperatures higher than the gas temperature at the 3’ level) significantly increase radiant heat transfer (flux) to the surface of both fuel packages and firefighters protective equipment.

Figure 4. Temperature at the 3’ Level

Note: Figure 4 illustrates temperature conditions starting eight minutes after ignition. The fire previously progressed through incipient and growth stages before beginning to decay due to lack of ventilation.

Why the Dramatic Change in Conditions?

As discussed in UL Tactical Implications Part 1, Fires in the contemporary environment progress from ignition and incipient stage to growth, but often become ventilation controlled and begin to decay, rather than continuing to grow into a fully developed fire. This ventilation induced decay continues until the ventilation profile changes (e.g., window failure due to fire effects, opening a door for entry or egress, or intentional creation of ventilation openings by firefighters. When ventilation is increased, heat release rate again rises and temperature climbs with the fire potentially transitioning through flashover to the fully developed stage (see Figure 4 and 5).

Figure 5. Fire Development in a Compartment

Captain James Mendoza of the San Jose (CA) Fire Department and CFBT-US Lead Instructor demonstrates the influence of ventilation on fire development using a small scale prop developed by Dr. Stefan Svensson of the Swedish Civil Contingencies Agency.

The prop used in this demonstration is a small, single compartment with a limited ventilation opening on the right side (which in a full size building could be represented by normal building leakage or a compartment opening that is restricted such as a partially open door or window). The front wall of the prop is ceramic glass to permit direct observation of fire conditions within the compartment.

As you watch this demonstration, pay particular attention to how conditions change as the fire develops and then enters the decay stage. In addition, observe how quickly the fire returns to the growth stage and develops conditions that would be untenable after the window is opened at 12:17.

Download Doll’s House Plans (or Doll’s House Plans: Metric) for directions on how to construct a similar small scale prop.

Fire development and changes in conditions following ventilation in this demonstration mirror those seen in the full scale experiments conducted by UL. Increasing ventilation to a ventilation controlled fire, results in increased heat release rate and transition from decay to the growth stage of fire development.

The same phenomena can be observed under fireground conditions in the following video clip of a residential fire in Dolton, Illinois (this is a long video, watch the first several minutes to observe the changes in fire behavior).

It appears that the front door was open at the start of the video clip and the large picture window on Side A was ventilated at approximately 00:47. Fire conditions quickly transition to the growth stage with flames exiting the window and door, causing firefighters on an uncharged hoseline that had been advanced into Floor 1, to quickly withdraw.

As discussed in UL Tactical Implications: Part 1:

• Fires that have progressed beyond the incipient stage are likely to be ventilation controlled when the fire department arrives.
• Ventilation controlled fires may be in the growth, decay, or fully developed stage.
• Regardless of the stage of fire development, when a fire is ventilation controlled, increased ventilation will always result in increased HRR.
• Firefighters and fire officers must recognize that the ventilation profile can change (e.g., increasing ventilation) as a result of tactical action or fire effects on the building (e.g., window failure).
• Firefighters and fire officers must anticipate potential changes in fire behavior related to changes in the ventilation profile and ensure that fire attack and ventilation are closely coordinated.

Coordinated Tactical Operations

Understanding how fire behavior can be influenced by changes in ventilation is essential. But how can firefighters put this knowledge to use on the fireground and what exactly does coordination of tactical ventilation and fire attack really mean?

Tactical ventilation can be defined as the planned, systematic, and coordinated removal of hot smoke and fire gases and their replacement with fresh air. Each of the elements of this definition is important to safe and effective tactical operations.

Ventilation (both tactical and unplanned) not only removes hot smoke, but it also introduces fresh air which can have a significant effect on fire behavior.

Tactical ventilation must be planned; these two elements speak to the intentional nature of tactical ventilation. Tactics to change the ventilation profile must be intended to influence the fire environment or fire behavior in some way (e.g., raise the level of the upper layer to increase visibility and tenability). The ventilation plan must also consider the flow path (e.g., vent ahead of, not behind, the attack team; vent in the immediate area of the fire, not at a remote location).

Tactical ventilation must be systematic, exhaust openings should generally be made before inlet openings (particularly when working with positive pressure ventilation or when taking advantage of wind effects).

And as pointed out in the UL Study (Kerber, 2011), tactical ventilation must be coordinated. Coordination of ventilation and other tactical operations requires consideration of sequence and timing:

Sequence: Ventilation may be completed before, during, or after fire attack has been initiated. Sequence will likely depend on the stage of fire development, burning regime, time required to reach the fire.

If the fire is small and staffing is limited, it may be appropriate to control the fire and then effect ventilation (e.g., hydraulic ventilation performed by the attack team). This approach minimizes potential fire growth,

In general, when the fire is ventilation controlled (as those beyond the incipient stage are likely to be), ventilation should not be completed unless the attack line(s) can quickly apply water to the seat of the fire. In a small, single family dwelling this may mean that the attack team is on-air, the line is charged, and the entry door is unlocked or has been forced and is being controlled (held closed). In a larger building, this may mean that the attack line has entered the structure and is in position to move onto the fire floor or into the fire area.

The key questions that must be answered prior to implementing tactical ventilation are:

1. What influence will these ventilation tactics have on fire behavior?
2. Are charged and staffed attack line(s) in place?
3. Will the attack team(s) be able to quickly reach the fire?
4. How will this impact crews operating on the interior of the building?

Coordination requires clear, direct communication between companies or crews assigned to ventilation, fire attack, and other tactical functions that are or will be taking place inside the building.

Important: While not a tactical implication directly raised by the UL study, another important consideration is the hazard of working without or ahead of the hoseline. While a controversial topic in the US fire service (where truck company personnel generally work on the interior without a hoseline), searching with a hoseline provides a means of protection and a defined exit path. Staffing is another key element of the operational context. If you do not have enough personnel to control the fire and search; in most cases it is likely the best course of action to control the fire and ensure a safer operating environment for search operations.

What’s Next?

The next tactical implication identified in the UL study (Kerber, 2011) examines information that may be obtained by reading the air track at the entry point opening. This implication will be expanded with a broader discussion of air track indicators and how related hazards can be mitigated to improve firefighter safety.

References

Kerber, S. (2011). Impact of ventilation on fire behavior in legacy and contemporary residential construction. Retrieved July 16, 2011 from http://www.ul.com/global/documents/offerings/industries/buildingmaterials/fireservice/ventilation/DHS%202008%20Grant%20Report%20Final.pdf

Impact of Ventilation on Fire Behavior

Earlier this year, Underwriters Laboratories (UL) conducted a series of full-scale experiments to determine the influence of ventilation on fire behavior in legacy and contemporary residential construction (see Did You Ever Wonder?).

UL University recently releases an on-line training program based on this research. Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction is an excellent examination of the influence of ventilation on fire behavior and discussion of the tactical implications of the lessons learned through this research.

Every Firefighter and Fire Officer should complete
this training program within the next 30 days!

Completion of this on-line program could be the most important 90 minutes of training that you complete in the next year! I do not make this statement lightly. Understanding the relationship between ventilation and fire behavior is a critical competency for firefighters and fire officers.

After completing this on-line training program, consider the following questions and discuss them with the firefighters and fire officers you work with:

• What are the indicators of a ventilation controlled fire?
• How do your forcible entry and door entry procedures influence fire behavior?
• How do you (or do you) coordinate fire attack and ventilation? How can tactical coordination be improved in your department?
• What hazards are presented when performing VES (Vent, Enter, & Search) under ventilation controlled conditions? How can these hazards be mitigated?
• What influence do closed doors have on the survivability profile (for either civilian occupants or trapped firefighters)?
• What other lessons can you draw from this important research?

Research Report

In addition to the on-line course, UL has published a comprehensive report on this important research projects: Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction.

Video

You can also download an excellent video illustrating the difference between fuel characteristics and loading in legacy and contemporary residential occupancies. This video is a tremendous tool to illustrate changes in the built environment to both firefighters and civilian audiences.

High Resolution Video

Low Resolution Video

Lima Backdraft

I am still working the report on my staff ride to the site of the 1997 backdraft at Luis Giribaldi Street and 28 de Julio Street in the Victoria section of Lima, Peru and should have it posted within the next week.

Ed Hartin, MS, EFO, MIFireE, CFO

Introduction

While formal learning is an essential part of firefighters’ and fire officers’ professional development, informal learning is equally important, with lessons frequently shared through the use of stores. Stories are about sharing knowledge, not simply about entertainment. It is their ability to share culture, values, vision and ideas that make them so critical. They can be one of the most powerful learning tools available (Ives, 2004). “Only by wrestling with the conditions of the problem at hand and finding his own way out, does [the student] think” (Dewey, 1910, p. 188).

Developing mastery of the craft of firefighting requires experience. However, it is unlikely that we will develop the base of knowledge required simply by responding to incidents. Case studies provide an effective means to build our knowledge base using incidents experienced by others. This case is particularly significant as the circumstances could be encountered by almost any firefighter.

Aim

Firefighters and fire officers recognize and respond appropriately to the hazards of ventilation controlled fires in small, Type V (wood frame), single family dwellings.

References

National Institute for Occupationsl Safey and Health (NIOSH). (2010). Death in the line of duty: Report F2010-10. Retrieved October 22, 2010 from http://www.cdc.gov/niosh/fire/pdfs/face201010.pdf.

Ives, B. (2004) Storytelling and Knowledge Management: Part 2 – The Power of Stories. Retrieved May 6, 2010 from http://billives.typepad.com/portals_and_km/2004/08/storytelling_an_1.html

Dewey, J. (1910) Democracy and education. New York: McMillan

Learning Activity

Review the incident information and discuss the questions provided. Focus your efforts on understanding the interrelated impact of ventilation and fire control tactics on fire behavior. Even more important than understanding what happened in this incident is the ability to apply this knowledge in your own tactical decision-making.

The Case

This case study was developed using NIOSH Death in the Line of Duty: Report F2010-10 (NIOSH, 2010).

On the evening of March 30, 2010, while operating at a fire in a small single family dwelling, Firefighter/Paramedic Brian Carey and Firefighter/Paramedic Kara Kopas were assigned to assist in advancement of a 2-1/2” handline for offensive fire attack and to support primary search. Shortly after entering the building conditions deteriorated and they were trapped by rapid fire progression. Firefighter Kopas suffered 2^nd and 3^rd degree burns to her lower back, buttocks, and right wrist. Firefighter Carey died from carbon monoxide poisoning and inhalation of smoke and soot. A 84 year old male civilian occupant also perished in the fire.

Figure 1. Side A Post Fire

Note: National Institute for Occupational Safety and Health (NIOSH)

Building Information

This incident involved a 950 ft² (88.26 m²), one-story, single family dwelling constructed in 1951. The house was of Type V (wood frame) construction with a hip roof covered with asphalt shingles. The roofline of the hip roof provided a small attic space. Sometime after the home was originally constructed an addition C was built that attached the house to a garage located on Side C. Compartment linings were drywall. The house, garage, and addition were all constructed on a concrete slab.

There were several openings between the house and addition, including two doors, and two windows (see Figure 3).

Note: The number and nature of openings between the garage and addition is not reported, but likely included a door and possibly a window (given typical garage construction). NIOSH investigators did not determine if the doors and windows between the house, addition, and garage were open or closed at the time of the fire as they were consumed by the fire and NIOSH did not interview the surviving occupant (S. Wertman, personal communication, November 17, 2010). The existence and position of the door shown in the wall between the addition and garage is speculative (based on typical design features of this type of structure).

Figure 2. Plot Plan and Apparatus Positioning

Figure 3. Floor Plan 17622 Lincoln Avenue

The Fire

Investigators believe that the fire originated in an addition that was constructed between the original home and the two-car garage. The surviving occupant reported that she observed black smoke and flames from underneath the chair that her disabled husband was sitting in.

The addition was furnished as a family room and fuel packages included upholstered furniture and polyurethane padding. The civilian victim also had three medical oxygen bottles (one D Cylinder (425 L) and two M-Cylinders (34 L). It is not know if the oxygen in these cylinders was a factor in fire development. The garage contained a single motor vehicle in the garage and other combustible materials.

After calling 911 and attempting to extinguish the fire, the female occupant exited the building. NIOSH Death in the Line of Duty Report 2010-10 did not specify this occupants egress path or if she left the door through which she exited open or closed (NIOSH did not interview the occupant, she was interviewed by local fire and law enforcement authorities). The NIOSH investigator (personal communications S. Wertman, November 17, 2010) indicated that the occupant likely exited through the exterior door in the addition or through the door on Side A. Give rapid development through flashover in the addition, it is likely that the exterior door in the addition or door to the garage was open, pointing to the likelihood that the occupant exited through this door. Subsequent rapid extension to the garage was likely based on design features of the addition and garage or some type of opening between these two compartments. As similar extension did not occur in the house, it is likely that the door and windows in the Side C wall of the house were closed.

In the four minutes between when the incident was reported (20:55 hours) and arrival of a law enforcement unit (20:59), the fire in the addition had progressed from the incipient stage to fully developed fire conditions in both the addition and garage.

Dispatch Information

At 2055 hours on March 30, 2010, dispatch received a call from a resident at 17622 Lincoln Avenue stating that her paralyzed husband’s chair was on fire and that he was on oxygen. The first alarm assignment consisting of two engines, two trucks, a squad, and ambulance, and fire chief was dispatched at 2057.

Table 1. On-Duty and Additional Unit Staffing of First Alarm Resources

Note: This table was developed by integrating data from Death in the Line of Duty Report 2010-10 (NIOSH, 2010).

Weather Conditions

The weather was clear with a temperature of 12^o C (53^o F). Firefighters operating at the incident stated that wind was not a factor.

Conditions on Arrival

A law enforcement officer arrived prior to fire companies and reported that the house was “fully engulfed” and that the subject in the chair was still in the house.

Truck 1220 (T-1220) arrived at 2101, observed that the fire involved a single family dwelling, and received verbal reports from law enforcement and bystanders that the male occupant was still inside. Note: The disabled male occupant’s last known location was in the addition between the house and garage, but it is unknown if this information was clearly communicated to T-1220 or to Command (E-534 Lieutenant).

Engine 534 (E-534) arrived just behind T-1220 and reported heavy fire showing. E-534 had observed flames from Side C during their response and discussed use of a 2-1/2” (64 mm) handline for initial attack.

Firefighting Operations

Based on the report of a trapped occupant, T-1220B (Firefighter and Apparatus Operator) prepared to gain entry and conduct primary search. Note: Based on data in NIOSH Death in the Line of Duty Report 2010-10, it is not clear that this task was assigned by the initial Incident Commander (Engine 534 Lieutenant). It appears that this assignment may have been made by the T-1220 Lieutenant, or performed simply as a default truck company assignment for offensive operations at a residential fire.

Upon arrival, the E-534 Lieutenant assumed Command and transmitted a size-up report indicating heavy fire showing. The Incident Commander(E-534 Lieutenant) assisted the E-534 Firefighter with removal of the 1-3/4” (45 mm) skid load from the solid stream nozzle on the 2-1/2” (64 mm) hose load and stretching the 2-1/2” (64 mm) handline to the door on Side A. The E-534 Apparatus Operator charged the line with water from the apparatus tank and then hand stretched a 5” supply line to the hydrant at the corner of Lincoln Avenue and Hawthorne Road with the assistance of a Firefighter from T-1220.

Figure 4. Initiation of Primary Search

The Incident Commander (E-534 Lieutenant) assisted T-1220B in forcing the door on Side A. T-1220B made entry without a hoseline and began a left hand search as illustrated in Figure 4, noting that the upper layer was banked down to within approximately 3’ (0.9 m) from the floor).

Arriving immediately after E-534, the crew of A-564 donned their personal protective equipment and reported to the Incident Commander at the door on Side A, where he and the E-534 Firefighter were preparing to make entry with the 2-1/2” hoseline. The Incident Commander then assigned A-564 to work with the E-534 Firefighter to support search operations and control the fire.

T-1220 initiated roof operations and began to cut a ventilation opening on Side A near the center of the roof. Note: Based on data in NIOSH Death in the Line of Duty Report 2010-10, it is not clear that this task was assigned by the initial Incident Commander (Engine 534 Lieutenant). It appears that this assignment may have been made by the T-1220 Lieutenant, or performed simply as a default truck company assignment for offensive operations at a residential fire.

As illustrated in Figure 5, a large body of fire can be observed on Side C and a bi-directional air track is evident at the point of entry on Side A with dark gray smoke pushing from the upper level of the doorway at moderate velocity. All windows on Sides A and B were intact, with evidence of soot and/or condensed pyrolizate on the large picture window adjacent to the door on Side A.

Figure 5. Conditions Viewed from the Alpha/Bravo Corner at Approximately

Note: Warren Skalski Photo from NIOSH Death in the Line of Duty Report F2010-10.

The Firefighter from E-534 took the nozzle and assisted by Firefighters Carey and Kopas (A-564) stretched the 2-1/2” (64 mm) handline through the door on Side A and advanced approximately 12’ (3.66 m) into the kitchen. As they advanced the hoseline, they were passed by T-1220B, conducting primary search. The E-534 Firefighter, Firefighter Kopas (A-564), and T-1220B observed thick (optically dense), black smoke had dropped closer to the floor and that the temperature at floor level was increasing.

Figure 6. Primary Search and Fire Control Crews

Questions

Take a few minutes and consider the answers to the following questions. Remember that it is much easier to sort through the information presented by the incident when you are reading a blog post, than when confronted with a developing fire with persons reported!

1. What B-SAHF (Building, Smoke, Air Track, Heat, & Flame) indicators were observed during the initial stages of this incident?
2. What stage(s) of fire and burning regime(s) were present in the building when T-1220 and E-534 arrived? Consider potential differences in conditions in the addition, garage, kitchen, bedrooms, and living room?
3. What would you anticipate as the likely progression of fire development over the next several minutes? Why?
4. How might tactical operations (positively or negatively) influence fire development?

Ed Hartin, MS, EFO, MIFireE, CFO

The ability to read the fire and predict likely fire behavior is a critical skill for both firefighters and fire officers. Previous posts have examined how to use the B-SAHF scheme to recognize critical fire behavior indicators and identify the stage of fire development, burning regime, and potential for extreme fire behavior such as flashover or backdraft. However, there is something missing!

Experience is critical to adapting standard procedures and practices to a complex and dynamic operational environment. However, learning about fire behavior and changes in fire conditions based on fireground observations are a bit like a black box test. Black box testing is a technique for testing computer software in which the internal workings of the item being tested are not known by the tester. This is not entirely true in the case of fire behavior, but there is much that we don�t know when assessing conditions on the fireground. How long has the fire been burning? What are the specific characteristics of the fuel? What sort of internal compartmentation is present? What exactly is the ventilation profile? Some of these factors can be determined during fire investigation and it is also possible to determine (with some degree of uncertainty) what influence these factors had on the outcome of the incident. Did you ever wonder how fire behavior would have changed if you had used different tactics? Unfortunately, in real life there are no �do overs�!

UL Tactical Ventilation Research Project

One of the people who has asked himself the question of what would have changed if different tactics were used is Underwriters Laboratories Fire Protection Engineer Steve Kerber.

Underwriters Laboratories (UL) has received a Firefighter Safety Research and Development Grant from the Department of Homeland Security (DHS). This research project will investigate and analyze the impact of natural horizontal ventilation on fire development and conditions in legacy (older, more highly compartmented) and contemporary (multi-level, open floor plan) residential structures.

Preliminary work has included review of literature related to horizontal ventilation and incidents in which ventilation had a significant influence on firefighter injuries and fatalities. In addition, UL has done preliminary work on the performance of various structural components such as single and multi-pane windows as preliminary input for design of full scale residential fire experiments.

In mid-December 2009, Steve Kerber met with the project advisory panel comprised of Captain Charles Bailey, Montgomery County (MD) Fire Department; Lieutenant John Ceriello New York City Fire Department, Firefighter James Dalton and Director of Training Richard Edgeworth, Chicago Fire Department, Chief Ed Hartin, Central Whidbey Island (WA) Fire & Rescue, Chief Otto Huber Loveland-Symmes (OH) Fire Department, and Chief Mark Nolan, Northbrook (IL) Fire Department. In addition, the advisory panel includes Fire Protection Engineers Dan Madrzykowski from the National Institute of Standards and Technology (NIST) and Dr. Stefan Svensson, a research and development engineer from the Swedish Civil Contingencies Agency.

Figure 1. Defining Experiment Parameters for the Contemporary Structure

The main task presented to the advisory panel at the first meeting was to aid in defining the parameters for the experiment; including fire location, changes in ventilation profile, timing of these changes, and instrumentation to measure effects on fire development and conditions.

UL Large Fire Research Facility

The ventilation experiments will be conducted at the UL Large Fire Research Facility in Northbrook, IL. From the exterior, this facility simply looks like a large industrial building (see Figure 2). However, the interior of the structure includes a unique facility for fire research.

Figure 2. UL Large Fire Research Facility

One of the facilities inside this building is a 100� x 120� (30.48 m x 36.58 m) with a ceiling height that is adjustable up to 50� (15.24 m) (see Figure 3). All of the smoke resulting from tests in this facility is exhausted through a system designed to oxidize unburned fuel and scrub hazardous products from the effluent prior to discharge to the atmosphere. Tests are monitored from a control room that overlooks the large burn room.

Figure 3. Large Burn Room

Over the next month, the two residential structures to be used for the ventilation experiments will be constructed inside the large burn room at the UL Large Fire Test Facility. After construction is complete, a series of 16 full scale fire experiments is planned to evaluate a range of different horizontal ventilation scenarios.

Research with the Fire Service

Steve Kerber has often stated that it is essential that scientists and engineers conduct research with, not for, the fire service. Engagement between researchers and firefighters on the street is essential in advancement of our profession. With this ventilation research project, Underwriters Laboratories is actively engaged in this process.

The outcome of this project will not simply be an academic paper (but there might be one or more of those as well). As part of the DHS grant, UL will be developing an on-line course to present the results of the experiments and their practical application on the fireground.

Happy Holidays,

Ed Hartin, MS, EFO, MIFireE, CFO

This morning I begin the process of relocation to beautiful Whidbey Island, Washington. Later this week I begin my new job as Fire Chief with Central Whidbey Island Fire & Rescue.

Coupeville Harbor at Sunrise

As I have been packing and preparing for my move all weekend, I have not had time to develop an in-depth Monday morning post. However, I did run across an interesting video clip a few weeks ago that ties in well with our ongoing effort to develop skill in reading the fire.

R-Fire

On March 27, 2009 the Emerson and Red Oak Fire Departments were dispatched for a residential fire at 901 Lowell Ave in Emerson, IA. First arriving companies observed a fire on Floor 1 and smoke throughout the structure.

The following video clip appears to have been shot early in incident operations as positive pressure ventilation is being implemented.

Download the B-SAHF Worksheet to use as a reminder while watching the video clip.

As you view the video clip, what do the fire behavior indicators (particularly smoke and air track) tell you about the stage of fire development, burning regime, and effectiveness of tactical operations?

Questions

In addition to your general observations of B-SAHF indicators while you watched the video the first time, consider the following questions:

• Watch the video clip again and examine conditions at the inlet between 0:21 and 0:25. What does the presence of smoke (and particularly dark smoke) pushing from the inlet indicate?
• Continue the video and examine conditions between 1:02 and 1:10. What do you observe at this point? What do smoke and air track conditions indicate now?
• Continue on and examine conditions closely between 2:28 and 2:48. What does the variation in smoke and air track indicators at different points on the exterior of the structure tell you?

Back on Schedule!

I plan to be back on track with the next post in the series examining nozzle techniques on Thursday, November 12. I have been having an e-mail conversation BC Mike Walker of the Oklahoma City Fire Department regarding nozzle techniques and flashover. Mike is working on a research project regarding �right for reach and left for life�. Interestingly, when I received Mike�s first e-mail, I was in the process of outlining an upcoming blog post on the concept of �Battle Drills� to deal with or escape from conditions such as those resulting from unplanned changes in ventilation (window failure, wind, etc.).

Ed Hartin, MS, EFO, MIFireE, CFO

Open Enrollment CFBT Level I & Instructor Courses

CFBT-US, LLC and the Northwest Association of Fire Trainers (NAFT) will be offering CFBT Level I and Instructor Courses at the Clackamas County (OR) Fire District I CFBT facility.

CFBT Level I
7-9 November 2009
Course Fee: $335

CFBT Instructor
9-13 November 2009
Course Fee: $915

Instructor course participants receive a copy of 3D Firefighting: Training, Techniques, & Tactics and an extensive 2-DVD library of CFBT resources including the CFBT Level I curriculum. For information on these courses download a NAFT CFBT Brochure and the CFBT Level I and CFBT Instructor Course Information Sheets.

CFBT Workshop in Sand�, Sweden

From 12-16 October 2009, I will be participating in a CFBT workshop in Sand�, Sweden along with a small group of instructors from around the world. We will be studying the compartment fire behavior curriculum at the Swedish Civil Contingencies Agency (Myndigheten f�r samh�llsskydd och beredskap (MSB)) College in Sand�.

Figure 1. Fire Behavior Training in Sand�

In January of 2009 MSB replaced the Swedish Rescue Services Agency, the Swedish Emergency Management Agency, and the Swedish National Board of Psychological Defense. The MSB maintains two fire service colleges, one in Sand� (see Figure 2) and the other in Revinge.

Figure 2. MSB College in Sand�

The International Conference of Fire and Rescue, Valdivia – Chile 2010 CIFR

My brothers with Company 1 �Germania� of the Valdivia, Chile Fire Department have taken on a tremendous task with delivery of the first International Conference of Fire & Rescue in Valdivia. The conference will be held 23-27 January 2010.

Conference presenters include a diverse cadre of instructors from around the world. I will be presenting a series of seminars on fire behavior as well as a hands-on CFBT workshop. Presentations will be simultaneously translated into English and Spanish (as applicable). Have a look at the Conference Web Site for more information on this tremendous learning opportunity.

NIOSH Death in the Line of Duty F2007-02

On November 23, 2006, Firefighter Steven Solomon, a 33-year-old career fire fighter was seriously injured during a ventilation induced flashover or related fire behavior event in an abandoned single story duplex in Atlanta, GA; he died as a result of these injuries 6 days later.

NOSH Report F2007-02 provides an excellent description of fire behavior indicators observed prior to the occurrence of extreme fire behavior and correctly identifies that increased ventilation without coordinated fire attack resulted in worsening fire conditions.

Several conclusions in the report were based on computational fluid dynamics (CFD) modeling using the National Institute of Standards and Technology (NIST) Fire Dynamics Simulator software. As discussed in a previous post computer modeling is an excellent tool, but it is important to understand both its capabilities and limitations (see Townhouse Fire-Washington, DC: Computer Modeling)

It is crucial to bear in mind that fire models do not provide a reconstruction of the reality of an event. They are simplified representation of reality that will always suffer from a certain lack of accuracy and precision. Under the condition that the user is fully aware of this status and has an extensive knowledge of the principles of the models, their functioning, their limitations and the significance attributed to their results, fire modeling becomes a very powerful tool (Dele�mont & Martin, J., 2007, p. 134).

Review NIOSH Report F2007-02 and see if you agree or disagree with the conclusions regarding the type of extreme fire behavior phenomena involved in this incident.

Ed Hartin, MS, EFO, MIFireE, CFO

This post continues study of an incident in a townhouse style apartment building in Washington, DC with examination of the extreme fire behavior that took the lives of Firefighters Anthony Phillips and Louis Mathews.

A Quick Review

Prior posts in this series, Fire Behavior Case Study of a Townhouse Fire: Washington, DC and Townhouse Fire: Washington, DC-What Happened examined the building and initial tactical operations at this incident. The fire occurred in the basement of a two-story, middle of building, townhouse style apartment with a daylight basement. This configuration provided an at grade entrance to the Floor 1 on Side A and at grade entrance to the Basement on Side C.

Engine 26, the first arriving unit reported heavy smoke showing from Side A and observed a bi-directional air track at the open front door. First alarm companies operating on Side A deployed hoselines into the first floor to locate the fire. Engine 17, the second due engine, was stretching a hoseline to Side C, but had insufficient hose and needed to extend their line. Truck 4, the second due truck, operating from Side C opened a sliding glass door to the basement to conduct search and access the upper floors (prior to Engine 17’s line being in position). When the door on Side C was opened, Truck 4 observed a strong inward air track. As Engine 17 reached Side C (shortly after Rescue 1 and a member of Truck 4 entered the basement) and asked for their line to be charged, and Engine 17 advised Command that the fire was small.

Extreme Fire Behavior

Proceeding from their entry point on Side C towards the stairway to Floor 1 on Side A, Rescue 1B and the firefighter from Truck 4 observed fire burning in the middle of the basement room. Nearing the stairs, temperature increased significantly and they observed fire gases in the upper layer igniting. Rescue 1B and the firefighter from Truck 4 escaped through the basement doorway on Side C as the basement rapidly transitioned to a fully developed fire.

Figure 1. Timeline Leading Up to the Extreme Fire Behavior Event

The timeline illustrated in Figure 1 is abbreviated and focuses on a limited number of factors. A detailed timeline, inclusive of tactical operations, fire behavior indicators, and fire behavior is provided in a subsequent section of the case.

After Engine 17’s line was charged, the Engine 17 officer asked Command for permission to initiate fire attack from Side C. Command denied this request due to lack of contact with Engines 26 and 10 and concern regarding opposing hoselines. Due to their path of travel around Side B of the building, Engine 17 had not had a clear view of Side A and thought that they were at a doorway leading to Floor 1 (rather than the Basement). At this point, neither the companies on Side C nor Command recognized that the building had three levels on Side C and two levels on Side A.

At this point crews from Engine 26 and 10 are operating on Floor 1 and conditions begin to deteriorate. Firefighter Morgan (Engine 26) observed flames at the basement door in the living room (see Figure 8 which illustrates fire conditions in the basement as seen from Side C). Firefighter Phillips (Engine 10) knocked down visible flames at the doorway, but conditions continued to deteriorate. Temperature increased rapidly while visibility dropped to zero.

As conditions deteriorated, Engine 26’s officer feels his face burning and quickly exits (without notifying his crew). In his rapid exit through the hallway on Floor 1, he knocked the officer from Engine 10 over. Confused about what was happening Engine 10’s officer exited the building as well (also without notifying his crew). Engine 26’s officer reports to Command that Firefighter Mathews was missing, but did not report that Firefighter Morgan was also missing. Appearing dazed, Engine 10’s officer did not report that Firefighter Phillips was missing.

Figure 2. Conditions on Side C at Aproximately 00:28

Note: From Report from the Reconstruction Committee: Fire at 3146 Cherry Road NE, Washington DC, May 30, 1999, p. 32. District of Columbia Fire & EMS, 2000.

Figure 3. Conditions on Side A at Aproximately 00:28

Note: From Report from the Reconstruction Committee: Fire at 3146 Cherry Road NE, Washington DC, May 30, 1999, p. 29. District of Columbia Fire & EMS, 2000.

Firefighter Rescue Operations

After the exit of the officers from Engine 26 and Engine 10, the three firefighters (Mathews, Phillips, and Morgan) remained on Floor 1. However, neither Command (Battalion 1) nor a majority of the other personnel operating at the incident recognized that the firefighters from Engines 26 and 10 had been trapped by the rapid extension of fire from the Basement to Floor 1 (see Figure 4).

While at their apparatus getting a ladder to access the roof from Side B, Truck 4B observed the rapid fire development in the basement and pulled a 350′ 1-1/2″ (107 m 38 mm) line from Engine 12 to Side C, backing up Engine 17.

Figure 4. Location of Firefighters on Floor 1

Note: Adapted from Report from the Reconstruction Committee: Fire at 3146 Cherry Road NE, Washington DC, May 30, 1999, p. 18 & 20. District of Columbia Fire & EMS, 2000 and Simulation of the Dynamics of the Fire at 3146 Cherry Road NE, Washington D.C., May 30, 1999, p. 12-13, by Daniel Madrzykowski & Robert Vettori, 2000. Gaithersburg, MD: National Institute of Standards and Technology.

Engine 17 again contacted Command (Battalion 1) and requested permission to initiate an exterior attack from Side C. However, the officer of Engine 17 mistakenly advised Command that there was no basement entrance and that his crew was in position to attack the fire on Floor 1. Unable to contact Engines 10 and 26, Command denied this request due to concern for opposing hoselines. With conditions worsening, Command (Battalion 1) requested a Task Force Alarm at 00:29, adding another two engine companies, truck company, and battalion chief to the incident.

Firefighter Phillips (E-10) attempted to retreat from his untenable position at the open basement door. He was only able to travel a short distance before he collapsed. Firefighter Morgan (E-26) heard a loud scream to his left and then a thud as if someone had fallen to the floor (possibly Firefighter Mathews (E-26)). Firefighter Morgan found the attack line and opened the nozzle on a straight stream, penciling the ceiling twice before following the hoseline out of the building (to Side A). Firefighter Morgan exited the building at approximately 00:30.

Rescue 1B entered the structure on Floor 1, Side A to perform a primary search. They crawled down the hallway on Floor 1 towards Side C until they reached the living room and attempted to close the open basement door but were unable to do so. Rescue 1 B did not see or hear Firefighters Mathews (E-26) and Phillips (E-10) while working on Floor 1. Rescue 1B noted that the floor in the living room was spongy. The Rescue 1 Officer ordered his B Team to exit, but instead they returned to the front door and then attempted to search Floor 2, but were unable to because of extremely high temperature.

Unaware that Firefighter Phillips (E-10) was missing, Command tasked Engine 10� and Rescue 1A, with conducting a search for Firefighter Mathews (E-26). The Engine 10 officer entered Floor 1 to conduct the search (alone) while instructing another of his firefighters to remain at the door. Rescue 1A followed Engine 26’s 1-1/2″ (38 mm) hoseline to Floor 1 Slide C. Rescue 1B relocated to Side B to search the basement for the missing firefighter.

The Engine 26 Officer again advised Command (Battalion 1) that Firefighter Mathews was missing. Engine 17 made a final request to attack the fire from Side C. Given that a firefighter was missing and believing that the fire had extended to Floor 1, Command instructed Engine 17 to attack the fire with a straight stream (to avoid pushing the fire onto crews working on Floor 1). At approximately 00:33, Battalion 2 reported (from Side C) that the fire was darkening down. Engine 14 arrived and staged on Bladensburg Road.

Command ordered a second alarm assignment at 00:34 hours. At 00:36, Command ordered Battalion 2 (on Side C) to have Engine 17 and Truck 4 search for Firefighter Mathews in the Basement. Engine 10’s officer heard a shrill sound from a personal alert safety system (PASS) and quickly located Firefighter Phillips (E-10). Firefighter Phillips was unconscious, lying on the floor (see Figure 4) with his facepiece and hood removed. Unable to remove Firefighter Phillips by himself, the officer from Engine 10 unsuccessfully attempted to contact Command (Battalion 1) and then returned to Side A to request assistance.

Command received a priority traffic message at 00:37, possibly attempting to report the location of a missing firefighter. However, the message was unreadable.

The Hazmat Unit and Engine 6 arrived and staged on Bladensburg Road and a short time later were tasked by Command to assist with rescue of the downed firefighter on Floor 1. Firefighter Phillips (E-10) was removed from the building by the Engine 10 officer, Rescue 1A, Engine 6, and the Hazardous Materials Unit at 00:45. After Firefighter Phillips was removed to Side A, Command discovered that Firefighter Mathews (E-26) was still missing and ordered the incident safety officer to conduct an accountability check. Safety attempted to conduct a personnel accountability report (PAR) by radio, but none of the companies acknowledged his transmission.

The Deputy Chief of the Firefighting Division arrived at 00:43 and assumed Command, establishing a fixed command post at the Engine 26 apparatus. Battalion 4 arrived a short time later and was assigned to assist with rescue operations along with Engines 4 and 14.

Firefighter Mathews was located simultaneously by several firefighters. He was unconscious leaning over a couch on Side C of the living room (see Figure 4). Firefighter Mathews breathing apparatus was operational, but he had not activated his (non-integrated) personal alert safety system (PASS). Firefighter Mathews was removed from the building by Engine 4, Engine 14, and Hazardous Materials Unit at 00:49.

Command (Deputy Chief) ordered Battalions 2 and 4 to conduct a face-to-face personnel accountability report on Sides A and C at 00:53.

Questions

1. Based on the information provided in the case to this point, answer the following questions:
2. National Institute for Occupational Safety and Health (NIOSH) Death in the Line of Duty Reports examining incidents involving extreme fire behavior often recommend close coordination of fire attack and ventilation.
3. Did the fire behavior in this incident match the prediction you made after reading the previous post (Towhouse Fire: Washington DC-What Happened)?
4. What type of extreme fire behavior occurred? Justify your answer?
5. What event or action initiated the extreme fire behavior? Why do you believe that this is the case?
6. How did building design and construction impact on fire behavior and tactical operations during this incident?
7. How might a building pre-plan and/or 360^o reconnaissance have impacted the outcome of this incident? Note that 360^o reconnaissance does not necessarily mean one individual walking completely around the building, but requires communication and knowledge of conditions on all sides of the structure (e.g., two stories on Side A and three stories on Side C).
8. How might the outcome of this incident have changed if Engine 17 had been in position and attacked the fire in the basement prior to Engines 26 and 10 committing to Floor 1?
9. What strategies and tactics might have been used to mitigate the risk of extreme fire behavior during this incident?

More to Follow

This incident was one of the first instances where the National Institute of Standards and Technology (NIST) Fire Dynamics Simulator (FDS) was used in forensic fire scene reconstruction (Madrzykowski & Vettori, 2000). Modeling of the fire behavior in this incident helps illustrate what was likely to have happened in this incident. The next post in this series will examine and expand on the information provided by modeling of this incident.

Ed Hartin, MS, EFO, MIFireE, CFO

References

District of Columbia (DC) Fire & EMS. (2000). Report from the reconstruction committee: Fire at 3146 Cherry Road NE, Washington DC, May 30, 1999. Washington, DC: Author.

Madrzykowski, D. & Vettori, R. (2000). Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510. August 31, 2009 from http://fire.nist.gov/CDPUBS/NISTIR_6510/6510c.pdf

National Institute for Occupational Safety and Health (NIOSH). (1999). Death in the line of duty, Report 99-21. Retrieved August 31, 2009 from http://www.cdc.gov/niosh/fire/reports/face9921.html

This post continues study of an incident that resulted in two line-of-duty deaths as a result of extreme fire behavior in a townhouse style apartment building in Washington, DC.

A Quick Review

The previous post in this series, Fire Behavior Case Study of a Townhouse Fire: Washington, DC examined building construction and configuration that had a significant impact on the outcome of this incident. The fire occurred in the basement of a two-story, middle of building, townhouse style apartment with a daylight basement. This configuration provided an at grade entrance to the Floor 1 on Side A and an at grade entrance to the Basement on Side C.

The fire originated in an electrical junction box attached to a fluorescent light fixture in the basement ceiling (see Figures 1 and 2). The occupants of the unit were awakened by a smoke detector. The female occupant noticed smoke coming from the floor vents on Floor 2. She proceeded downstairs and opened the front door and then proceeded down the first floor hallway towards Side C, but encountered thick smoke and high temperature. The female and male occupants exited the structure, leaving the front door open, and made contact with the occupant of an adjacent unit who notified the DC Fire & EMS Department at 0017 hours.

Dispatch Information

At 00:17, DC Fire & EMS Communications Division dispatched a first alarm assignment consisting of Engines 26, 17, 10, 12, Trucks 15, 4, Rescue Squad 1, and Battalion 1 to 3150 Cherry Road NE. At 0019 Communications received a second call, reporting a fire in the basement of 3146 Cherry Road NE. Communications transmitted the update with the change of address and report of smoke coming from the basement. However, only one of the responding companies (Engine 26) acknowledged the updated information.

Weather Conditions

Temperature was approximately 66^o F (19^o C) with south to southwest winds at 5-10 mi/hr (8-16 km/h), mostly clear with no precipitation.

Conditions on Arrival

Approaching the incident, Engine 26 observed smoke blowing across Bladensburg Road. Engine 26 arrived at a hydrant at the corner of Banneker Drive and Cherry Road at 00:22 hours and reported smoke showing. A short time later, Engine 26 provided an updated size-up with heavy smoke showing from Side A of a two story row house. Based on this report, Battalion 1 ordered a working fire dispatch and a special call for the Hazmat Unit at 00:23. This added Engine 14, Battalion 2, Medic 17 and EMS Supervisor, Air Unit, Duty Safety Officer, and Hazmat Unit.

Firefighting Operations

DC Fire and EMS Department standard operating procedures (SOP) specify apparatus placement and company assignments based on dispatch (anticipated arrival) order. Note that dispatch order (i.e., first due, second due) may de different than order of arrival if companies are delayed by traffic or are out of quarters.

Standard Operating Procedures

Operations from Side A

The first due engine lays a supply line to Side A, and in the case of basement fires, the first line is positioned to protect companies performing primary search on upper floors by placing a line to cover the interior stairway to the basement. The first due engine is backed up by the third due engine. The apparatus operator of the third due engine takes over the hydrant and pumps supply line(s) laid by the first due engine, while the crew advances a backup line to support protection of interior exposures and fire attack from Side A.

The first due truck takes a position on Side A and is responsible for utility control and placement of ladders for access, egress, and rescue on Side A. If not needed for rescue, the aerial is raised to the roof to provide access for ventilation.

The rescue squad positions on Side A (unless otherwise ordered by Command) and is assigned to primary search using two teams of two. One team searches the fire floor, the other searches above the fire floor. The apparatus operator assists by performing forcible entry, exterior ventilation, monitoring search progress, and providing emergency medical care as necessary.

Operations from Side C

The second due engine lays a supply line to the rear of the building (Side C), and in the case of basement fires, is assigned to fire attack if exterior access to the basement is available and if it is determined that the first and third due engines are in a tenable position on Floor 1. The second due engine is responsible for checking conditions in the basement, control of utilities (on Side C), and notifying Command of conditions on Side C. Command must verify that the first and third due engines can maintain tenable positions before directing the second due engine to attack basement fires from the exterior access on Side C.

The second due truck takes a position on Side C and is responsible for placement of ladders for access, egress, and rescue on Side C. The aerial is raised to the roof to provide secondary access for ventilation (unless other tasks take priority).

Command and Control

The battalion chief positions to have an unobstructed view of the incident (if possible) and uses his vehicle as the command post. On greater alarms, the command post is moved to the field command unit.

Notes: This summary of DC Fire & EMS standard operating procedures for structure fires is based on information provided in the reconstruction report and reflects procedures in place at the time of the incident. DC Fire & EMS did not use alpha designations for the sides of a building at the time of this incident. However, this approach is used here (and throughout the case) to provide consistency in terminology.

First due, Engine 26 laid a 3″ (76 mm) supply line from a hydrant at the intersection of Banneker Drive and Cherry Road NE, positioned in the parking lot on Side A, and advanced a 200′ 1-1/2″ ( 61 m 38 mm) pre-connected hoseline to the first floor doorway of the fire unit on Side A (see Figures 1 and 2). A bi-directional air track was evident at the door on Floor 1, Side A , with thick (optically dense) black smoke from the upper area of the open doorway. Engine 26’s entry was delayed due to a breathing apparatus facepiece malfunction. The crew of Engine 26 (Firefighters Mathews and Morgan and the Engine 26 Officer) made at approximately 00:24.

Figure 1. Plot and Floor Plan-3146 Cherry Road NE

Note: Adapted from Report from the Reconstruction Committee: Fire at 3146 Cherry Road NE, Washington DC, May 30, 1999, p. 18 & 20. District of Columbia Fire & EMS, 2000; Simulation of the Dynamics of the Fire at 3146 Cherry Road NE, Washington D.C., May 30, 1999, p. 12-13, by Daniel Madrzykowski & Robert Vettori, 2000. Gaithersburg, MD: National Institute of Standards and Technology, and NIOSH Death in the Line of Duty Report 99 F-21, 1999, p. 19.

Engine 10, the third due engine arrived shortly after Engine 26, took the hydrant at the intersection of Banneker Drive and Cherry Road, NE, and pumped Engine 26’s supply line. After Engine 10 arrived at the hydrant, the firefighter from Engine 26 who had remained at the hydrant proceeded to the fire unit and rejoined his crew. Engine 10, advanced a 400′ 1-1/2″ (122 m 38 mm) line from their own apparatus as a backup line. Firefighter Phillips and the Engine 10 officer entered through the door on Floor 1, Side A (see Figure 2) while the other member of their crew remained at the door to assist in advancing the line.

Truck 15, the first due truck arrived at 00:23 and positioned on Side A in the parking lot behind Engine 26. The crew of Truck 15 began laddering Floor 2, Side A, and removed kitchen window on Floor 1, Side A (see Figure 2). Due to security bars on the window, one member of Truck 15 entered the building and removed glass from the window from the interior. After establishing horizontal ventilation, Truck 15 accessed the roof via a portable ladder and began vertical ventilation operations.

Engine 17, the second due engine, arrived at 00:24, laid a 3″ (76 mm) supply line from the intersection of Banneker Drive and Cherry Road NE, to a position on Cherry Road NE just past the parking lot, and in accordance with department procedure, stretched a 350′ 1-1/2″ (107 m 38 mm) line to Side C (see Figure 2).

Approaching Cherry Road from Banneker Drive, Battalion 1 observed a small amount of fire showing in the basement and assigned Truck 4 to Side C. Battalion 1 parked on Cherry Road at the entrance to the parking lot, but was unable to see the building, and proceeded to Side A and assumed a mobile command position.

Second due, Truck 4 proceeded to Side C and observed what appeared to be a number of small fires in the basement at floor level (this was actually flaming pieces of ceiling tile which had dropped to the floor). The officer of Truck 4 did not provide a size-up report to Command regarding conditions on Side C. Truck 4, removed the security bars from the basement sliding glass door using a gasoline powered rotary saw and sledgehammer. After clearing the security grate Truck 4, broke the right side of the sliding glass door to ventilate and access the basement (at approximately 00:27) and then removed the left side of the sliding glass door. The basement door on Side C was opened prior to Engine 17 getting a hoseline in place and charged. After opening the sliding glass door in the basement, Truck 4 attempted to ventilate windows on Floor 2 Side C using the tip of a ladder. They did not hear the glass break and believing that they had been unsuccessful; they left the ladder in place at one of the second floor windows and continued with other tasks.

Figure 2. Location of First Alarm Companies and Hoselines

Note: Adapted from Report from the Reconstruction Committee: Fire at 3146 Cherry Road NE, Washington DC, May 30, 1999, p. 27. District of Columbia Fire & EMS, 2000.

Unknown to Truck 4, these windows had been left open by the exiting occupants. Truck 4B (two person team from Truck 4) returned to their apparatus for a ladder to access the roof from Side C. Rescue 1 arrived at 00:26 and reported to Side C after being advised by the male occupant that everyone was out of the involved unit (this information was not reported to Command). Rescue 1 and Truck 4 observed inward air track (smoke and air) at the exterior basement doorway on Side C and an increase in the size of the flames from burning material on the floor.

Engines 26 and 10 encountered thick smoke and moderate temperature as they advanced their charged 1-1/2″ (38 mm) hoselines from the door on Side A towards Side C in an attempt to locate the fire. As they extended their hoselines into the living room, the temperature was high, but tolerable and the floor felt solid. It is important to note that engineered, lightweight floor support systems such as parallel chord wood trusses do not provide reliable warning of impending failure (e.g., sponginess, sagging), failure is often sudden and catastrophic (NIOSH, 2005; UL, 2009).

Prior to reaching Side C of the involved unit, Engine 17 found that their 350′ 1-1/2″ (107 m 38 mm) hoseline was of insufficient length and needed to extend the line with additional hose.

Engine 12, the fourth arriving engine, picked up Engine 17’s line, completed the hoselay to a hydrant on Banneker Drive (see Figure 2). The crew of Engine 12 then advanced a 200′ 1-1/2″ (61 m 38 mm) hoseline from Engine 26 through the front door of the involved unit on Side A and held in position approximately 3′ (1 m) inside the doorway. This tactical action was contrary to department procedure, as the fourth due engine has a standing assignment to stretch a backup line to Side C.

Rescue 1’s B Team (Rescue 1B) and a firefighter from Truck 4 entered the basement without a hoseline in an effort to conduct primary search and access the upper floors via the interior stairway. Engine 17 reported that the fire was small and requested that Engine 17 apparatus charge their line.

Questions

Consider the following questions related to the interrelationship between strategies, tactics, and fire behavior:

1. Based on the information provided to this point, what was the stage of fire development and burning regime in the basement when Engine 26 entered through the door on Floor 1, Side A? What leads you to this conclusion?
2. What impact do you believe Truck 4’s actions to open the Basement door on Side C will have on the fire burning in the basement? Why?
3. What is indicated by the strong inward flow of air after the Basement door on Side C is opened? How will this change in ventilation profile impact on air track within the structure?
4. Did the companies at this incident operate consistently with DC Fire & EMS SOP? If not, how might this have influenced the effectiveness of operations?
5. Committing companies with hoselines to the first floor when a fire is located in the basement may be able to protect crews conducting search (as outlined in the DC Fire & EMS SOP). However, what building factors increased the level of risk of this practice in this incident?

More to Follow

My next post will examine the extreme fire behavior phenomena that trapped Firefighters Phillips, Mathews, and Morgan and efforts to rescue them.

Remember the Past

This week marked the anniversary of the largest loss of life in a line-of-duty death incident in the history of the American fire service. Each September, we stop and remember the sacrifice made by those 343 firefighters. However, it is also important to remember and learn from events that take the lives of individual firefighters. In an effort to encourage us to remember the lessons of the past and continue our study of fire behavior, each month I include brief narratives and links to NIOSH Death in the Line of Duty reports and other documentation in my posts.

September 9, 2006
Acting CAPT Vincent R. Neglia
North Hudson Regional Fire & Rescue Department, NJ

Captain Neglia and other firefighters were dispatched to a report of fire in a three-story apartment building in Union City. Upon their arrival at the scene, firefighters found light smoke and no visible fire. Based on reports that the structure had not been evacuated, Captain Neglia and other firefighters entered the building to perform a search. Due to the light smoke conditions, Captain Neglia was not wearing his facepiece.

Captain Neglia was the first firefighter to enter an apartment. Conditions deteriorated rapidly as fire in the cockloft broke through a ceiling . Captain Neglia was trapped by rapid fire progress and subsequent collapse. Other firefighters came to his aid and removed him from the building. Captain Neglia was transported to the hospital but later died of a combination of smoke inhalation and burns.

NIOSH did not investigate and prepare a report on the incident that took the life of Captain Neglia.

Ed Hartin, MS, EFO, MIFireE, CFO

References

District of Columbia (DC) Fire & EMS. (2000). Report from the reconstruction committee: Fire at 3146 Cherry Road NE, Washington DC, May 30, 1999. Washington, DC: Author.

Madrzykowski, D. & Vettori, R. (2000). Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510. August 31, 2009 from http://fire.nist.gov/CDPUBS/NISTIR_6510/6510c.pdf

National Institute for Occupational Safety and Health (NIOSH). (1999). Death in the line of duty, Report 99-21. Retrieved August 31, 2009 from http://www.cdc.gov/niosh/fire/reports/face9921.html

National Institute for Occupational Safety and Health (NIOSH). (2005). NIOSH Alert: Preventing Injuries and Deaths of Fire Fighters Due to Truss System Failures. Retrieved August 31, 2009 from http://www.cdc.gov/niosh/fire/reports/face9921.html