Ottawa Firefighters’ Occupational Exposures to PAHs

and Other Environmental Mutagens


Jennifer L.A. Keir 1, Umme S. Ahktar 1, Paul A. White 1, 2, David M.J. Matschke 3, Hing Man Chan 1,

Tracy L. Kirkham 4, Jules M. Blais 1


1 Department of Biology, University of Ottawa, Ottawa, Canada

2 Environmental Health Science and Research Bureau, Health Canada, Ottawa, Canada

3 Ottawa Fire Services, Ottawa, Canada

4 Occupational & Environmental Health Division, University of Toronto, Toronto, Canada

Image 1: Ottawa firefighters at an on-shift fire Photo: © Scott Stilborn


   Firefighters experience above average risks of injury and chronic disease. Occupational exposures to combustion emissions are of concern as emissions can include mutagens and carcinogens. Few studies have examined firefighters’ exposures to combustion emissions, and those that have examined exposures during training exercises. This study examined Ottawa Fire Services (OFS) firefighters’ occupational exposures to combustion emissions during on-shift fire suppression. It was the first of its kind to investigate on-shift, emergency fire suppression using sets of samples including personal air from the fire itself and wipe and urine samples from both pre- and post-fire.


Three areas were investigated:

1. Firefighters’ secondary exposures

2. Firefighters’ exposures during emergency, on-shift fire events

3. The ability of current OFS cleaning protocols to remove contaminants


   Firefighters can potentially be exposed to a mixture of different chemicals depending on the nature of the fire. Two groups of chemicals, metals and polycyclic aromatic hydrocarbons (PAHs), are most often studied because of their known toxicity and are among the most prevalent contaminants found in the air during a fire. Thus, PAHs, antimony, cadmium, and lead were measured in this study.


1. Firefighters’ secondary exposures

   Air samples were collected from inside fire halls to investigate if firefighters’ experience secondary exposures to combustion emissions. At three OFS station, air samples from the vehicle bay were collected using a high volume air sampler (depicted below) and a personal air sampler was used for inside the fire truck cab.

Image 2: Air samples were collected from inside fire stations’ vehicle bays and fire truck cabs. A high volume sampler was used to collect particulates on a filter and volatiles on a polyurethane foam underneath the filter.



• Average total PAH concentrations measured in vehicle bays were 2 times higher than typical urban air values (Dann, 1998).

• Average total PAH and antimony concentrations inside fire truck cabs were significantly higher than vehicle bays and the office (reference site).  

• All air concentrations of total PAHs, antimony, cadmium, and lead were well below the adjusted long term exposure limit (ALEL) calculated based on the exposure standards set by Ontario Ministry of Labour and the Occupational Safety and Health Administration (OSHA).


Dann, T. (1998). “Ambient Air Measurements of Polycyclic Aromatic Hydrocarbons (PAH), Polychlorinated Dibenzo-p-Dioxins (PCDD) and Polychlorinated Dibenzofurans in Canada (1987-1997).” Report AAQD 97-3.


Government of Alberta (2011). The Effects of Unusual Work Schedules and Concurrent Exposures on Occupational Exposure Limits (OELs).


 2. Exposures during on-shift, emergency fire suppression

   To investigate firefighters’ combustion emission exposure from on-shift fires, volunteer participants were recruited from four different OFS stations. Participants had to be non smokers, live with non smokers, and agree avoid non-occupational exposures to combustion emissions (e.g., barbequed and smoked foods, bonfires, etc.).

   At the beginning of each shift, participants would provide a urine sample and wipes of their skin (i.e., forehead, neck, and wrist), personal protective equipment (PPE) (i.e., jacket, breathing apparatus belt, and pants), and under gear (e.g., undershirt and underwear). These were used as baseline, pre-exposure values. Personal air samplers were attached to their PPE so that in the event of a fire, the individual would start the pump, remove the cap, and collect air during fire suppression operations. After a fire, participants would provide the same wipe samples (i.e., skin, PPE, and undergear) and collect all urine for 18 hours afterwards. This was required as some of the compounds measured take several hours to be metabolized and excreted.

Image 3: Summary of sample collection collected January – October 2015 to investigate firefighters’ exposures during on-shift, emergency fire suppression events. Photos by A. Wu & D. Matschke.



   Samples were collected from January to October 2015. During the study period, 29 air samples with paired wipe samples (pre- and post-fire) were collected from 16 participants across 18 separate fires, with several instances of multiple participants present at the same fire. All fires were structural (i.e., involved structural components of residential or commercial buildings), except for one container fire (i.e., garbage or recycling bin).


• Some concentrations of PAHs and lead in personal air collected during fire events were above the occupational exposure limit set by the Ontario Ministry of Labor.

 Firefighters properly wearing PPE (including SCBA) are not expected to be exposed to dangerous levels. However, improper use or premature removal of SCBA, and/or handling of contaminated PPE and equipment, may contribute to increased exposure.


• Concentrations of PAHs, antimony, and lead on skin and PPE after a fire were significantly elevated compared to levels on skin before a fire (i.e. background levels). Wipe samples of clothing collected after a fire had significantly elevated lead concentrations.

 This illustrates the importance of showering and properly decontaminating your PPE and clothing after a fire.


• Levels of urinary PAH metabolites, mutagenic activity, and antimony were significantly elevated after a fire.

 This suggests that contact with combustion emissions during fire suppression is contributing to elevated exposures to selected substances (i.e., chemicals entering the body). Observed relationships between PAHs on the skin and metabolites in the urine suggest that skin contact is an important route of exposure. This further illustrates the importance of properly showering and decontaminating after firefighting events.


3. The ability of current OFS cleaning protocols to remove contaminants

   The ability of current cleaning protocols to remove contaminants was investigated by analysing wipes of PPE after a fire & before cleaning, and after a fire. Samples were collected at the OFS cleaning facility.



   The current cleaning procedure for firefighters’ personal protective equipment significantly decreases levels of PAHs, cadmium, antimony, and lead.


Will The Measured Levels Affect Firefighters’ Health? Should I Be Concerned?

   Everyone is exposed to potentially hazardous chemicals on a daily basis; many substances are naturally found in the environment, and exposures are unavoidable. For example, PAHs are commonly found in urban air and cooked foods, and everyone is exposed to some extent. Exposures can occur in the home, as well as during occupational and recreational activities outside the home. With the exception of urinary cadmium, there are no guideline values to determine whether you should be concerned about your exposure. Therefore, there is not enough scientific information to determine what levels of exposure can result in harm.      

  If you are concerned about your results, and your exposures to the agents examined in this study, you may consult with the project’s principal investigator and/or the project’s occupational hygienist. In addition, you can consult your family doctor for a medical opinion regarding potential health risks. Information about the substances examined in this study and sources of additional information can be found