Diesel Exhaust Emission at Fire Station Engine Bay Areas and Implications for Station Work/Living Areas

ABSTRACT

Diesel exhaust comprises of a complex mixture of both particulate matter and gaseous substances including diesel particulate matter (DPM), polyaromatic hydrocarbons (PAH), inorganic particles, nitrogen dioxide (NO2) and sulfur dioxide (SO2), carbon monoxide (CO), volatile organic materials (VOC's). Diesel exhaust has been classified as a class 2A - probable human carcinogen by the International Agency for Research on Cancer.

Queensland Fire and Rescue fire fighters have raised concerns about their exposure to diesel exhaust within fire stations. However, there is little if any data available to assess the extent of Queensland fire fighters exposure to diesel exhaust.

A variety of emission products were investigated and the values obtained compared to established workplace exposure standards. Where workplace exposure standards have not been established a value was selected after reviewing accepted industry standards. These standards were adopted as the levels of concern (LOC). The emission products characterised included: Diesel particulate matter (dpm) ; Polyaromatic hydrocarbons (PAH); Volatile organic compounds (VOC) such as benzene and formaldehyde; and Simple inorganic compounds like carbon monoxide.

The emission product of greatest concern is the dpm. The study focused on characterising emissions within the context of the normal operation of a fire station and included specific activities and work areas. These included: ten hour environmental background measurement; ten hour exposure in areas such as office, engine bay and mess area; fire appliance - emergency response; fire appliance-returning to fire station; and fire appliance- start of operational shift check.

The study also considered fire fighter personal protective clothing storage.
Seven fire stations were selected to participate in the study after considering criteria such as turnout frequency, age and building design. The participating fire stations were: Cairns; Townsville; Rockhampton; Maroochydore; Caboolture; Loganlea; and Anzac Avenue (T oowoomba).

The exposure after ten hours to the diesel exhaust is summarised. In general, the VOC, simple inorganic compounds and PAH values were many hundreds of times less than the LOC and were similar to the external environmental values obtained. The average external dpm value was 0.002 mg/m3 EC-elemental carbon (range: <0.001 to 0.007 mg/m3 EC). The highest dpm value obtained in an engine bay was concentration (0.009 mg/m3 EC) at Anzac Avenue. The average values in all areas of the station ranged from 0.002 to 0.003 mg/m3 EC.

The exposure after the fire appliance emergency response to the diesel exhaust is summarised. The VOC, simple inorganic compounds and PAH values were below the established LOCs. The highest dpm value obtained was 0.027 mg/m3 EC at Rockhampton fire station. The average value was 0.009 mg/m3 EC and corresponds to ca. 10 times less than the LOC (0.1 mg/m3 EC).

The exposure after the fire appliance return to station to the diesel exhaust is summarised. The VOC, simple inorganic compounds and PAH values were below the established LOCs. The highest dpm value obtained was 0.032 mg/m3 EC at Rockhampton fire station. The average value was 0.013 mg/m3 EC and corresponds to ca. 8 times less than the LOC (0.1 mg/m3 EC).

The exposure after the fire appliance start of operational shift check to the diesel exhaust is summarised. The exposure was measured where possible the engine bay doors were closed and any mechanical ventilation ceased to simulate the worst case situation. The VOC and PAH values were below the established LOCs. Except in the case where a Firepac 3000 Mk 3 appliance used. The highest dpm value obtained (excluding the Firepac mark III 3000) was 0.08 mg/m3 EC at Anzac Avenue fire station and is ca. 1.2 times less than the LOC. The average value was 0.044 mg/m3 EC and corresponds to less than half the LOC (0.1 mg/m3 EC). However, the Firepac 3000 Mk 3 appliance result was 0.73 mg/m3 and ca. 8 times above the LOC.

The results concerning emissions from fire fighter protective clothing where detected were many times less than the corresponding LOC's. The results suggest the fire fighter exposure to diesel exhaust emissions are less than the established LOC except in the case where the Firepac 3000 Mk 3 appliance was used during a start of operational shift check.


A series of recommendations have been provided to the QFRS for consideration to further reduce fire fighter exposures to diesel exhaust emissions. The recommendations included: Further investigate the Firepac 3000 Mk 3 performance and provide recommendations to minimise fire fighter exposure; Actions to further minimise fire fighter exposures and improve fire fighter personal protective clothing storage at the participating fire stations, other fire stations and future fire stations; Consider the purpose of the fire appliance start of operational shift check; and Communicate the findings to QFRS fire fighters.


EXPERIMENTAL DESIGN 


The experiments focussed on the five typical station activities: 

Typical urban background immediately adjacent to the fire station; 
Typical 10 hour (day shift) work day; 
Start of Shift checks; 
Turn-out from fire station of standard number of appliances; and
Return to station of standard number of appliance. 

The appliance start of shift and turn-out/return trials were based on the standard station appliance compliment and standard turn-out, except Cairns station where the technical rescue appliance was not present. In this trial a larger aerial appliance was used in its place. Thus, some stations have one appliance and others have two appliances turning out and returning to station for the trials.

Experiments were designed to measure where diesel exhaust emissions were most likely to be greatest across the fire station and the cumulative exposure over a 10 hour workday. The day shift was selected because of the more frequent appliance movement, fire fighters being more active during the day and the greater potential for contribution to fire fighter exposure from external sources. Thus, information about the typical background levels of airborne contaminants immediately adjacent to the fire stations was required. The contaminants of interest were selected, based on the typical diesel combustion products, the chemical nature of the airborne contaminants (complexity contaminants such as formaldehyde or naphthalene), and the acute or chronic respiratory irritations they cause (such as sulphur dioxide and diesel particulate matter) are: 

Acid gases - carbon monoxide, hydrogen sulphide, sulfur dioxide and nitrogen dioxide; 
Total volatile organic compounds – tvoc Specific volatile organic compounds – Benzene, toluene, xylene and hexane; 
Oxygenated hydrocarbons – Aldehydes such as formaldehyde and acrolein; 
Particulates - Polyaromatic hydrocarbons (PAHs); and diesel particulate matter (DPM).

Background Airborne Contaminants 

There is an environmental background of the airborne contaminants in the urban environment typically from motor vehicles or other human activity. The concentrations of airborne contaminants are influenced by many factors including weather, time, location, and adjacent industries. Determining the typical background the airborne contaminants at each station provides a reference to (i) establish a baseline for all seven fire stations; and (ii) comparative concentration by which to compare the results obtained at each station during the trials. This approach provided confidence in the data collected for fire fighter exposure during the 10 hr day shift was not biased by any external event. Background concentrations were obtained during the same 10 hr time period as the station measurements, with small sampling location variations due to particular station characteristics. The measurement and sample collection devices were located outside the fire station engine bays and closest to the nearest/busiest roadway, typically at 10 - 15 cm from the ground.

10 hr Day shift 

A fire station has a background level of airborne contaminants and the concentrations are affected by many factors including weather, time, location and adjacent industries. The determination of fire fighter exposure during a 10 hour day shift provides information on typical station exposures, which can be compared to typical background levels and exposures at other stations participating in this study. Using survey responses, several station areas of concern were selected. Sampling locations located in the following areas of concern varied slightly between stations because of particular station characteristics: 

Engine bay – midway next to the exhaust pipe of the main appliance (ca. 1.5 m from floor); 
Duty office – desk or other furniture (ca. 0.8 m from floor) and adjacent to door; 
Mess room - table (ca. 0.8 m from floor) nearest to engine bay entrance; Dormitory – closest to engine bay (ca. 0.4 m from floor) and adjacent to door; and
PPE locker – adjacent to ensemble exhibiting greatest evidence of soot and marking (ca. 0.5 m from floor). 

The sampling heights best represented the likely breathing zones of the fire fighters undertaking activities in these areas.

Start of Shift Check 

The start of shift check involves physically checking equipment and operation of all mechanical devices such as the appliance engine, generators and ancillary petrol driven equipment. The standard process was undertaken for all appliances housed in the engine bay. The engine bay doors (front and rear) were closed for the test duration (except Cairns and Townsville where the front engine bay doors were closed, but the rear doors were either absent). The exact sample location varied from station to station because of the particular engine bay characteristics. The measurement and sample collection devices were typically at 1.5 m from the ground and adjacent to the exhaust of the main appliance (c.a. behind the vehicle cab on the off-side of the appliance). The activity specific measurements ceased when the start of shift check was completed. Together with the 10 Hr engine bay continuous samplers, a number of instantaneous measurements and active sampling techniques were applied for the activities as listed in table.

Turn-Out Simulations 

The standard simulated turn-out scenario involved monitoring during the following activities;
1. simultaneously commencing monitoring, opening engine bay doors and starting the fire appliance(s), 
2. idling fire appliance(s) for 60 seconds; 
3. accelerating appliance to leave the station,
4. doors closed immediately after appliance(s) have left engine bay; and
5. Monitoring ceased two minutes after commencing the trial. 

This simulation was repeated at least 10 – 15 times to ensure a sufficient volume of air was passed through the collection filters, and the subsequent laboratory analysis limit of detection (LOD) was appropriate for the occupational exposure concentrations. After completion of each simulation, all engine bay doors were opened for ca. 5 minutes to ventilate the engine bay before any further turn-out or return simulations were performed. The sampling locations were the same as the start of shift sampling location for each station. Together with the 10 Hr engine bay continuous samplers, a number of instantaneous measurements and active sampling techniques were applied for the activities as listed in table 2.6 below.

Return to Station Simulations 

The standard simulated return to station scenario involved monitoring during the following activities; 
1. idling appliance for 60 seconds outside station with engine bay doors closed; 
2. simultaneously commencing monitoring and opening engine bay doors; 
3. fire appliance(s) driven into place and shut down as per normal procedure; 
4. doors closed immediately after appliance(s) entered engine bay; and 
5. Monitoring ceased two minutes after commencing the trial. 

This simulation was repeated at least 10 – 15 times to ensure a sufficient volume of air was passed through the collection filters, and the subsequent laboratory analysis limit of detection (LOD) was appropriate for the occupational exposure concentrations. After completion of each simulation, all engine bay doors were opened for ca. 5 minutes to ventilate the engine bay before any further turn-out or return simulations were performed. The sampling locations were the same as the start of shift sampling location for each station. Together with the 10 Hr engine bay continuous samplers, a number of instantaneous measurements and active sampling techniques were applied for the activities as listed in table 2.7 below.

Table on how many turned out etc. 

All stations recorded actual and simulated turn-out and return to station activities. These trials were performed one the day prior to the 10 Hr continuous monitoring due to time of trails and the amount of sampling required to obtain samples that could be analysed with a low enough level of detection. The number of simulation turn-outs was dependent on the minimum LOD required and operational requirements. The start of shift checks and continuous monitoring were performed on the second day of the trials. The table below shows the amount of appliance activity during the sampling trials


Analytical Methods 

The limit of detection (LOD) is the smallest concentration that can be detected with reasonable certainty for a given analytical procedure, and the reporting limit (R.L) is the minimum concentration of an analyte that can be measured within specified limits of precision and accuracy of the analytical procedure. These are important distinctions and the concentrations from the analytical laboratory report refer to the reporting limit (R.L). 

Colourimetric Dräger Tubes 

A range of Dräger stain tubes were used to identify and semi-quantify the airborne contaminants; benzene, sulphur dioxide, and nitrogen dioxide. 

The measurements were obtained following the instructions provided by Dräger. A sealed colourimetric tube was broken at both ends and inserted into a Dräger hand pump. Typically 10 pumps were undertaken unless specified by the manufacturer and the tube held at about 1.5 m from the ground. The tube was directly read after the completion of the recommended pumps. The characteristics of each tube is shown in the following table


Active Air Sampling using SKC pumps 

Diesel Particulate Matter (DPM) sampling 

DPM samples were collected following the principles of the reported method NIOSH Method 5040 using SKC universal PCXR4 variable flow meters. T

he diesel particulate matter was collected on SKC 37-mm diameter cassettes with Quartz-Filter fibre (DPM cassettes). The cassettes were connected to SKC PCXR8 Universal Sample Pump using tygon tubing. Samples were typically collected at a flow rate of 1.8 – 2.0 L min-1for the 10 Hr samples and 4.0 – 5.9 L min-1 for the 2 minute simulated trails. The flow rate of each pump was checked immediately prior to and at the completion of sampling period using a Bios International Corp. DryCal DC-Lite primary flow meter. 

Travel blanks were packed with samples at each station for transport to the analysing laboratory for blank subtraction of Elemental carbon (EC) and organic carbon (OC). The average OC loading for the travel blanks was 11.137μg per filter, which represents roughly 30% of the average filter loading. The average EC loading for the travel blank filters was 0.012 μg per filter, which was 1.2% of average EC loading.

DPM analysis 

All DPM Cassettes were analysed for total carbon (TC), organic (OC) and elemental carbon (EC) via the NIOSH Method 5040 by Coal Services Pty Ltd, using a Sunset Laboratories thermo-optical instrument. Carbon speciation analysis was carried out by placing a 8.04 cm2 punched section of a cartridge quartz fibre filter from a 37mm SKC DPM in helium purged flow furnace. The temperature was increased step wise (ca. 500 - 700°C) to initially remove all organic carbon followed then by carbonates. Pyrolised products were flushed off as CO2 and catalytically converted to CH4 for detection by an FID detector. The oven was then cooled (ca. 25°C), a 2% O2/He mixture introduced and the temperature again increased step wise (ca. 850°C) to oxidise elemental carbon which is then converted to methane (CH4) for detection. The laser transmission was monitored through the filter during the cycle to minimise interferences caused by elemental carbon formed during the pyrolysis of organic carbon. A known volume of CH4 was injected into the furnace for calibration purposes after each cycle. 

An analysis LOD of ~0.001 mg/m3 for organic, elemental or total carbon has been reported by the AIOH26. This figure is also quoted by the analyst on the basis of information from the instrument manufacture.

Polycyclic Aromatic Hydrocarbons (PAH) sample collection 

PAH samples were collected following the principles of the NIOSH Method 5515 sing SKC Leland legacy variable flow meters.

The PAH (particulate and vapour phase) was collected in SKC 22 x 100 mm borosilicate glass tubes, containing Polyurethane foam (PUF) / Tenax / PUF layers. The filters were connected to SKC Leland legacy pumps using tygon tubing, and samples collected at a flow rate of 4.0 – 5.0 L min-1. The flow rate of each pump was checked immediately prior and after the completion of sampling using a Bios International Corp. DryCal DC-Lite primary flow meter.

Travel blanks were packed with samples at each station for transport to the analysing laboratory for blank subtraction. The average PAH loading for the travel blanks was typically 20 – 30 ng per tube, which represents roughly <0.01% of the average filter loading.

PAH analysis 

The PAH samples were analysed by the Qld Health Forensic and Scientific Services using the principles USEPA TO-13A Method. The PUF and Tenax layers were co-extracted using Accelerated Solvent Extraction (ASE) on a Dionex ASE100 using hexane as the extracting solvent. Prior to extraction the samples were spiked with a deuterated PAH mixture (1ng/μL) corresponding to the PAHs of interest. The ASE conditions were:

Cell size: 34mL 
Temperature: 100°C 
Static Time: 5 min 
Flush Volume: 60% 
Purge Time: 250 s 
Static Cycles: 3

The extracting solvent was concentrated using Kuderna-Danish apparatus on a heated water bath. The final 200μL volume was analysed using GCMS. Quantification was achieved using a ratio of d-PAH:PAH in an external calibration curve. Analysis LOR was typically 2 ng/m3 for individual PAHs as reported by QHFSS.

Note: Two concentrations were considered, one with and one without naphthalene due to the analysing laboratory caveats on the analysis - any result over 100,000 pg/m3 is outside of the calibration range and should be viewed as an estimated result. This approach is likely to provide a more conservative concentration for naphthalene.

Volatile Organic Compounds (VOC)

Sample collection onto Tenax 

SKC aircheck 2000 variable flow meters were used to collect VOC samples onto SKC stainless steel tubes packed with a tenax/carboxyn/tenax matrix (spiked with the deuterated internal standards - dichlorethane, benzene, toluene, styrene, and dichlorbenzene), following the principles the US-EPA TO-17 method. The tubes were connected to SKC pumps using tygon tubing. Flow rates of 10 – 20 ml min-1 were typically used for samples collected over 10 hours, and 80 – 100 mL min-1 for samples collected over two minutes. The flow rate of each pump was checked immediately prior to and at the completion of sampling period using a Bios International Corp. DryCal DC-Lite primary flow meter. Travel blanks were packed with samples at each station for transport to the analysing laboratory for blank subtraction. The VOC samples were analysed according to the established Qld Health Forensic and Scientific Services Method using the principles of US-EPA method TO-17. VOCs were thermally desorbed from the tubes and analysed by GC-MS spectrometry. The LOR for individual VOCs was typically 50ng per tube

Sample collection into Canister 

VOC samples were collected in SKC Silcosteel-treated interior (fused silica) 15 L canisters that had been put under vacuum and controlled with a 10 Hr restrictor regulator. The VOC samples were analysed according to the established Qld Health Forensic and Scientific Services Method using the principles of US-EPA method TO-15. VOC were collected in syringes from the canisters and analysed by GC-MS spectrometry. The LOR for individual VOCs was typically 1 part per billion ( ppb)


DNPH-Aldehydes 

The aldehyde samples were collected following the principles of the USEPA TO-11A method using SKC aircheck 2000 variable flow meters. The aldehydes were collected on a hydroxymethyl piperazine (DNPH) matrix housed in glass sorbent tubes (manufactured by Supelco, Inc.). The tubes were connected to SKC Aircheck 2000 pumps using tygon tubing. Samples were typically collected at a flow rate of 80 – 100 mL min-1 for the samples collected over 10 Hr, and 180 – 200 mL min-1 for samples collected over two minutes. The flow rate of each pump was checked immediately prior to and at the completion of sampling period using a Bios International Corp. DryCal DC-Lite primary flow meter. Travel blanks were packed with samples at each station for transport to the analysing laboratory for blank subtraction. The aldehyde samples were solvent extracted from the tubes and analysed using HPLC according to the established Qld Health Forensic and Scientific Services Method using the principles of US-EPA method TO-11A. The LOR for individual aldehydes ranged from 0.3 to 1 μg per tube.

Passive Tenax-Volatile Organic Compounds (VOC)

VOCs were collected onto SKC passive badges comprising of Tenax placed in a polypropylene housing containing a number of inlet holes. The sampler is opened by removing a cover to expose the holes to the air and is closed by replacing the cover. Travel blanks were packed with samples at each station for transport to the analysing laboratory for blank subtraction. The VOC samples were analysed according to the established Qld Health Forensic and Scientific Services Method using the principles of US-EPA method TO-17. The VOC - both aliphatic and aromatic organics were thermally desorbed from the tubes and analysed by GC-MS spectrometry. The LOR for individual VOCs was typically 50ng per badge.

Passive DNPH-Aldehydes 

The aldehydes were collected onto SKC passive badges comprising of silica gel filter paper treated with 2,4-dinitrophenylhydrazine (DNPH) placed in a polypropylene housing containing a number of inlet holes. The sampler is opened by sliding a cover to expose the holes to the air and is closed by replacing the sliding cover. The sampler contains two filter compartments. 

Travel blanks were packed with samples at each station for transport to the analysing laboratory for blank subtraction. The aldehyde samples were solvent extracted from the badges and analysed according to the established Qld Health Forensic and Scientific Services Method using the principles of US-EPA method TO-6A. The LOR for individual aldehydes ranged from 0.6 μg per filter. 

Lower Flammability Limit, Hydrogen Sulfide, Oxygen Carbon Monoxide 

The four gases: carbon monoxide (CO); oxygen (O2); lower flammability limit (LFL); and hydrogen sulfide (H2S) were measured using a Rae Systems MultiRae Plus four gas detector. The instruments were calibrated at Queensland Health Forensic Scientific Services following the established process and challenged immediately prior to use. The flow rate was approximately 250 ml/min and all collected data was logged. The instrument characteristics are described below.

Total volatile hydrocarbons (TVOC) 

The TVOC were measured using a Rae systems MiniRae 2000 Photoionisation detector and a ppbRae Photoionisation detector equipped with 10.6 eV UV lamps. The measurements are described against the calibrant gas (isobutylene), and logged over one minute averaging periods . The peak concentrations within these averaging periods are plotted against the time of day.

Level of Concern 

A workplace exposure standard (ES) represents an airborne concentration of a particular substance within the breathing zone of a worker, and exposure to which the present state of knowledge should not cause any health effects or undue discomfort to nearly all people. Exposure Standards have generally been developed on the basis of: 

8 hour work shift; 
Average person is working at a “normal” level of intensity; 
Normal climatic conditions are present; and 
16 hours break between shifts

Safe Work Australia publishes the National Exposure Standards45 for many airborne contaminants, but not mixtures. The established concentrations that exist have been used as a basis to define levels of concern (LOC). The LOC for diesel particulate matter, which been discussed previously in chapter, is a peak concentration meaning that no limit should exceed the concentration in any work period. If the duration of a workers exposure is greater than 8 hours the ES can be revised by using the equation.

SUMMARY OF ALL FIRE STATION RESULTS

The seven stations used in the trials, Cairns, Townsville, Rockhampton, Maroochydore, Caboolture, Loganlea and Anzac Avenue (Toowoomba) showed that the ambient air quality in Fire stations across the state was typically at or below the outside ambient air, except for the short term activity start of shift when some engine bays showed elevated levels of the contaminates of concern. All result showed that at no time was the ambient within the stations above any 10 Hr corrected exposure standard.

Atmospheric Contaminants – nitrogen dioxide and sulfur dioxide 

The airborne concentration of sulphur dioxide was below the Limit of Detection (LOD) (< 0.5 ppm) for the all activities. Similarly, the airborne concentration of nitrogen dioxide was at or below the LOD (≤ 0.5 ppm) for the all activities, except the 33 minute start of shift checks at Loganlea Fire Station (0.75 ppm), which was ca. half of the 10 Hr time corrected workplace exposure standard (ES10) of 2 ppm.

Atmospheric Contaminants – carbon monoxide and hydrogen sulfide 

An average carbon monoxide (CO) background concentration of 0.7 ppm (range: 0.1 to 1.3 ppm) was measured outside all fire stations, which is consistent with the 2007 Qld Ambient Air Quality Data46 Brisbane CO average concentration of 1.1 ppm (range: 0.3 ppm to 3.9 ppm).

Generally, the highest concentrations of CO detected within the fire stations were in the engine bays and PPE lockers, which is consistent with station activities/design and where fire appliances/equipment are housed/used. A number of PPE lockers were open areas attached to the engine bays. The highest average CO concentration was measured during the 20 minute start of shift checks in the Rockhampton engine bay (2.7 ppm), which was ca. 4 times higher than the average outside concentration, but more than 7.5 times lower than the ES10 (21 ppm).

Generally, the average hydrogen sulfide (H2S) concentrations obtained within the stations (0.1ppm) was equal to the average outside concentration of H2S (0.1 ppm - range: 0.01 to 0.4 ppm). The highest fire station area average was the Loganlea dormitory (0.3 ppm), which is ca. 3 times higher than the average outside concentration, but ca. 23 times lower than the ES10 (7 ppm).

Atmospheric Contaminants – total volatile organic compounds 

The total volatile organic compounds (tvoc) average background concentration obtained outside all fire stations was 0.5 ppm (range: <0.1 to 3.6 ppm). There is no established national exposure standard for tvocs, however the QFRS adopts a level of concern (LOC) of 0.5 ppm for application at emergency incidents. The highest outside average obtained was Anzac avenue (4.1 ppm), which is ca. 8 times higher than the QFRS LOC of 0.5 pp

Generally, the highest tvoc concentrations within the fire stations were in the PPE lockers, (average 0.6 ppm - range: from <0.1 to 0.6 ppm), which is similar to the CO results. This is consistent with station activities and design, where the PPE lockers were typically open areas attached to the engine bays. The highest fire station concentration was the Loganlea engine bay (0.2 ppm), which is ca. 3 times lower than the average background concentration, and ca. 2 times lower than QFRS LOC (0.5 ppm).

Atmospheric Contaminants –VOCs of Interest – hexane, benzene, toluene and xylene 

The 2009 Qld Ambient Air Quality Data46 for Brisbane shows an average hexane concentrationof (1.1 ppb), benzene concentration(1.2 ppb), toluene concentration(1.3 ppb), and xylene concentration(25 ppb, based on 5 ppb of p-xylene which makes up 20% of total xylenes). The average background concentration obtained outside all fire stations for these vocs was; hexane 1.1 ppb (range: 1 to 1.7 ppb), benzene 1 ppb (range: 0.5 to 1 ppb); toluene 2.1 ppb (range: 1 to 3.7 ppb) and xylene 2.2 ppb (range: 2 to 3 ppb).

Generally, the levels of hexane and benzene were at or below the reporting limit (1 ppb) within the fire stations. However, higher concentrations of hexane were observed in the engine bay (3.2 ppb) and duty office (3.4 ppb) of Anzac Avenue, both of which are ca. 4000 times less than the ES10 (14000 ppb). Care should be taken with these higher results as they were obtained using passive diffusion badges. The major source of elevated benzene concentrations in the fire stations were in the engine bays. The highest measurement was in the Maroochydore engine bay (4.7 ppb), which is ca. 5 times higher than the average background benzene concentration, but ca. 140 times less than the ES10 (700 ppb). The Maroochydore concentration is similar to the ambient quality33 in a Brisbane industrial suburb. Bitumen laying was occurring adjacent to Maroochydore station during the trial.

The average toluene background concentrations for all stations were generally at or below the reporting limit (1 ppb) of the analysis. Like the benzene result, the highest toluene concentrations were in the engine bays of the fire stations. The highest engine bay result was at Loganlea (17 ppb), which is more than 2050 times lower than the 10 Hr time corrected exposure standard (ES10) of 35000 ppb, and significantly below the odour threshold (160 ppb). Anzac avenue had the highest readings in most areas of the station, which may have resulted from recent renovations (painting).

The average xylene background concentrations in all stations, except Maroochydore, Loganlea and Anzac Avenue, were at or below the reporting limit (2.2 ppb). In the same manner as benzene and toluene, the highest concentrations were observed in the engine bays. The highest fire station concentration obtained was Loganlea (13.5 ppb), which and ca. 2 times less than the corrected total xylene concentration(25 ppb) in ambient air, more than 4140 times lower than the ES10 (56000 ppb) and more than 1400 times less than the xylene odour threshold (20000 ppb).

These results show that no station area exceeded any occupational exposure limits for the vocs of interest.

Atmospheric Contaminants – Aldehydes 

The average total aldehyde background concentration outside all fire stations was 35 ppb (range: 17 to 47 ppb). Generally, the highest aldehyde concentrations detected within the fire stations were in the dormitories and PPE lockers, which were both similar to the ambient outside concentrations. This would be expected due to outside air being drawn into the station areas through air conditioners, and little ventilation within the station areas c.f the engine bays. The highest fire station concentration was the Loganlea dormitory (54 ppb), which is ca. 1.5 times higher than the average outside concentration, but similar to the Loganlea outside average (44 ppb), and considerably less than the 10 Hr corrected exposure standards for any of the individual aldehydes such as formaldehyde and acrolein.

Atmospheric Contaminants – Particulate Matter 

The average background concentrations of total Polyaromatic hydrocarbons (PAHs) and total diesel particulate matter (DPM) outside all fire stations was 0.14 μg/m3 (range: 0.05 to 0.23 μg/m3) and 0.002 mg/m3 EC (range: <0.001 to 0.007 mg/m3 EC), respectively. Generally, the highest concentrations of both PAHs and DPM within the fire stations were in the engine bay, which is expected due to the appliance engines being diesel based. The highest fire station PAH concentration was the Loganlea engine bay (1.4 μg/m3), which is 10 times higher than the average outside concentration, and 100 times lower than the 10 Hr corrected exposure standard ES10 (140 μg/m3). The highest fire station DPM concentration was the Anzac Avenue engine bay (0.009 mg/m3 EC), which is ca. 10 times lower than the ESDPM of 0.1 mg/m3 EC.

Of the three specific activities of interest, start of shift checks, turn-out and return simulations, the start of shift checks typically produced the highest concentrations of PAH and DPM. The average DPM concentration obtained for the start of shift check without a Firepac 3000 Mk 3 appliance present was 0.044 mg/m3 EC, and with a Firepac 3000 Mk 3 appliance present was 0.14 mg/m3 EC. The highest fire station concentrations were in Anzac Avenue engine bay (0.08 mg/m3 EC without Firepac 3000 Mk 3 and 0.73 mg/m3 EC with a Firepac mark III 3000). However, the concentration with the Firepac 3000 Mk 3 did not exceed the ESDPM of 0.1 mg/m3 EC.
