CONTROLLING DIESEL EXHAUST EMISSIONS AT THE FIRE STATION

CONTROLLING DIESEL EXHAUST EMISSIONS AT THE FIRE STATION

Firefighters wear protective clothing and self-contained breathing apparatus (SCBA) to limit their exposure to various hazards on the foreground. Yet, they can be as exposed to hazards while off the fireground. Exposure to diesel fuel emissions from fire apparatus within the fire station represents such a hazard. Continued exposure to diesel fuel emissions has been linked to cancer and other serious health disorders. Fire departmerits must act to reduce this exposure.

BACKGROUND

Diesel engines, used in fire apparatus, produce a mixture of toxic particulates and gases resulting from the combustion process. The composition of this exhaust product depends on several factors such as the specific fuel used, temperature of the engine, condition of the engine, and cleanliness of the air intake filter, among others. An analysis of general diesel engine exhaust has revealed a variety of extremely toxic substances at significant concentrations, including the following:

• nitrogen oxides: Any combustion in air produces various nitrogen oxides. Shortterm exposures can cause respiratory tract irritation and infections. Long-term exposures result in lung tissue damage and difficulty in breathing.
• carbon monoxide: Always produced as
• a by-product of combustion, high-level exposure causes death by tying up the blood’s hemoglobin and preventing the body from taking in oxygen. Exposure at lower concentrations causes headaches, dizziness, weakness, and neurological problems.
• volatile organic compounds (VOCs): These carbon-based chemicals include benzene, toluene, phenol, and chlorinated solvents, many of which cause a variety of adverse health effects such as headaches, nausea, neurological disorders, respiratory irritation, and liver damage. Some VOCs are known or suspected carcinogens (cancercausing substances).
• polyaromatic nuclear hydrocarbons (PNAs): This class of relatively large, complex chemicals are formed principally during combustion processes. In diesel exhaust, they often adhere to the soot particles. Most PNAs are documented carcinogens.

Much of the diesel exhaust, including the smaller soot particles, is invisible; exposure cannot always be detected. Furthermore, diesel exhaust can penetrate clothing, furniture, and other items with which firefighters have routine contact. It later can be released or absorbed into the firefighters’ skin.

STUDIES HIGHLIGHT HAZARDS

Many studies over the past several years point to an alarmingly high incidence of cancer and other health problems among firefighters:

• The International Association of Fire Fighters (IAFF) lists cancer as one of the major occupational hazards facing firefighters today.
• A study of Seattle firefighters shows a high level of mortality from diseases such as lung cancer, nonmalignant respiratory disease, and cardiovascular disease.’
• An analysis of firefighter deaths in the Boston area indicated a three-to-one increase in firefighter cancers when compared with the general population.
• In Los Angeles, cancer mortality among surviving firefighters is elevated for all lung
• and circulatory system

Concerns over repeated diesel exhaust exposures at the fire station are well-founded. The National Institute for Occupational Safety and Health (NIOSH) and the U. S. Occupational Safety and Health Administration (OSHA), through toxicological studies, have declared human exposure to diesel exhaust a potential occupational carcinogenic

A 1985 lAFF-commissioned study, which involved measuring diesel exhaust emissions at selected fire stations in New York, Boston, and Los Angeles, indicated that the most significant source of firefighter exposure to diesel exhaust was the exhaust that remained in the station after the engine The study identified some variations based on differences in climate, station design, number of runs per tour, and whether the firefighters smoked or not. From these findings, the IAFF study concluded: “Even with the uncertainties in the reported studies, apparent prudent public heath practices would require that steps be taken to limit firefighter exposure to diesel emissions.”

Later studies substantiated this problem and showed signdleant diesel exhaust emissions at smaller, less busy fire stations.As early as 1986, the New Jersey Department of Health distributed a bulletin alerting fire departments within the state of this

AVAILABLE SOLUTIONS AND THEIR MERITS

Various methods have been suggested for reducing diesel exhaust emissions at fire stations.” They take three forms:

1. Engineering controls: Involve methods that reduce the amount of toxic substances released by the diesel engine. Some research has indicated that engineering controls are best for reducing diesel exhaust emissions, since this approach eliminates much of the hazard before it is

This system is based on the use of cleaner burning fuels, better fuel ignition, and improved particulate exhaust traps. One approach involves using special catalytic converters designed to transform diesel exhaust into less harmful emissions more effectively.

A second approach involves more stringent emission standards for diesel engines built after 1995, as mandated by the U.S. Environmental Protection This solution is not currently available and will be very expensive for the fire service to implement if retrofitting were attempted. The newer generation of diesel engines still will produce some exhaust containing hazardous chemicals. As these newer diesel engines remain in service, their effectiveness in reducing exhaust will diminish as the engine no longer operates at optimum performance levels. Interim solutions, such as after-market special filters attached to the apparatus tailpipe, may appear to clean exhaust by removing visible particulates, but hazardous gases still can pass through and remain within the fire stations. Catalytic converters may also fail to remove all harmful diesel emissions.

2. Ventilation: Increases the flow of clean air to affected areas by adding apparatus room exhaust fans and, in some cases, providing a “positive pressure” in the living and work areas. Ambient “general” ventilation is the least desirable

One approach is diluting diesel exhaust gases with fresh air and keeping contaminated air from entering living or work spaces within the station. In its simplest form, the apparatus bay doors are left open for several minutes after the dieselpowered apparatus has left, allowing fresh air to enter the apparatus room. Typically, this approach also uses large-capacity fans to exhaust diesel emission, creating a negative pressure within the apparatus bay, thus allowing clean air to rush in. Additional ventilation control can be provided by the station’s heating, ventilation, and air-conditioning system to “over” pressure living or work areas.

This approach does not guarantee removal of all diesel exhaust because of “dead” air spaces within the station. Proper design of a ventilation system usually requires extensive modifications to the station at a very high cost. Moreover, this approach does not keep exhaust from becoming absorbed by clothing and equipment (which may be stored in or near the apparatus bay) or other textile/plastic materials within the station.

3. Source capture: Entails placing hosecollection devices directly on the apparatus exhaust pipe and venting the emissions into the atmosphere. Exhaust source capture is considered the most reliable means for reducing or eliminating exposure to diesel exhaust emissions in the fire station. However, this method has space requirements, and under certain conditions, a temperature inversion may occur, affecting the upward movement of products released to the atmosphere.

This solution consists of attaching a collection tube to the apparatus exhaust pipe and using a high-powered fan to draw the exhaust gases through the tube to be discharged to the outside atmosphere. This system involves the following: an automatic disconnect nozzle that allows vehicles to drive into and out of the fire station with the hoses still attached to the exhaust system (the pickup hose safely disconnects from the vehicle and is retracted into the building, permitting automatic doors to close); automatic activation via an in-line pressure switch when the apparatus engine is started or when apparatus bay doors open (ensuring consistent use); and timers to run exhaust fans until all residual gases have been removed from the system (manual operation is also provided).

Given the high incidence of cancer among firefighters, each fire department should take immediate steps to reduce the level of diesel exhaust emissions within its fire stations. While there are certain limitations with any system, to date, engineering controls and source capture have been shown to be optimum methods for reducing these emissions.

Endnotes

1. M.T. Grossi, J.B. Cropper. A.Stem, L. Todd. “Evaluation of Diesel Exhaust Exposure in New York City Fire Houses,” New York Department of Health. Feb. 1986.
2. J. Giarrizzo, “Cancer and Fire Fighting,” Fire Engineering, Sept. 1990, 65-66, 68-69.
3. N. Heyer, N.S. Weiss. P. Demers, L. Rosenstock, “Cohort Mortality Study of Seattle Fire Fighters, 19451983,” Am. J. Indus. Med. 1990, 17:493-504.
4. W.A. Musk. J.M. Peters, D.H. Wegman. “Lung Function in Fire Fighters. I: A Three Year Follow-Up of Active Subjects,” Am. J. Pub. Health-. 1977. 67(7):8689.
5. S.S. Lewis, H R. Bierman. M R. Faith. “Cancer Mortality Among Los Angeles City Fire Fighters.” L.A. Fire Department Report. Dec. 1982.
6. NIOSH Current Intelligence Bulletin 50. Carcinogenic Effects of Exposure to Diesel Exhaust. 1988. DHHS (NIOSH) Publication No. 88-116, U.S. Govt. Printing Office. Washington. D.C.
7. J.R. Froines, W.C. Hinds. R.M. Duffy. E.J. LaFuente. M.V. Liu. “Exposure of Fire Fighters to Diesel Emissions in Fire Stations.” Am. Indus. Hygiene Assn. J. 1987, 48(3):202-207.
8. W.C. Kinsey, “Firefighters and Diesel Emissions: A Current Study of Workplace Exposure,” 1991. Exec. Dev. Ill Research Paper. National Fire Academy. Emmitsburg, Md.
9. E.R. Weixeldorfer, “The Monitoring of Diesel Exhaust Emissions in Three Selected Kansas City. Missouri, Fire Stations”; 1992, Exec. Fire Ofcr. Program Paper, NFA, Emmitsburg, Md.
10. Information Bulletin, Diesel Exhaust in Fire Stations, N.J. Department of Health. Trenton, N.J.. Sept. 1986.
11. W.C. Peters. “Diesel Soot: An Exhausting Problem,” Fire Engineering. Mar. 1992, 47-51.
12. E.A. Pfieffer. “Don’t Let Smoke Get in Your Eyes,” Fire Chief, Apr. 1992, 126-128.
13. G.M. Sachs, “Safety Begins in the Fire Station,” Fire Command, July 1988. 15-17, 54.
14. K.A. Van Atta, “Strategies for Reducing Diesel Exhaust Exposure of Fire Fighters.” 1992. Exec. Fire Ofcr. Program Paper. NFA. Emmitsburg, Md.
15. S. Edwards. “Summary of the Views on Diesel Exhaust in Fire Departments,” 1AFF, Washington, D.C., Dec. 1989.
16. Proposed Rules. Environmental Protection Agency. 40 CFR Part 86. Vol. 57. No. 104. U.S. Gov’t. Printing Office. W ashington, D.C.. May 1992.
17. C. Roseboro. “Reducing Fire Fighter Exposure to Diesel Emissions”; 1992, Exec. Fire Ofcr. Program Paper. NFA. Emmitsburg, Md.