Exposure of Firefighters to Diesel Emissions in Fire Stations,

ABSTRACT

Personal sampling techniques were used to evaluate firefighter exposure to particulates from diesel engine emissions. Selected fire stations in New York, Boston and Los Angeles were studied. Firefighter exposure to total particulates increased with the number of runs conducted during an 8-hr period. In New York and Boston where the response level ranged from 7 to 15 runs during an 8-hr shift, the resulting exposure levels of total airborne particulates from diesel exhaust were 170 to 480 ug/ m3 (TWA). Methylene chloride extracts of the diesel particulates averaged 24% of the total. The authors’ findings suggest that additional research is necessary to assess fire station concentrations of vehicle
diesel exhaust that may have adverse health consequences to firefighters.

METHODS

Firefighter exposure to diesel exhaust was evaluated in ten fire stations: four in New York City, two in Boston and four in Los Angeles, All fire stations studied were two- or three- story buildings, with the exception of one single-story station in Boston. With the exception of one Boston fire station, all kitchens and television rooms were on the first floor and adjacent to the main equipment floor. There were significant differences in fire station configuration, particularly
the relative juxtaposition of the eating and sleeping quarters, the TV room, exercise area, and offices around the main equipment floor. All fire stations studied housed two companies of firefighters — a truck company and an engine company. Some stations had a third diesel-powered vehicle, a chief’s car. During daylight hours and up to about 10:00 p.m., the majority of firefighters studied spent most of their time in the kitchen or TV room or on the main floor of the fire station.

Personal sampling was used to measure exposure to total airborne particulates in the fire stations. For evaluation the authors selected a combination of firefighters that was representative of the workforce, including approximately equal numbers from engine and truck companies. In general, the authors sought participation from nonsmokers and did not differentiate on the basis of rank, Du Pont P-2500 pumps (Du Pont Company) were used at a flow rate of 2 L/min. Teflon®-coated glass fiber filters were used to determine the methylene chloride soluble fraction of the total particulates. Pumps were calibrated before and after each 8-hr sampling period. There was a study team member in each fire station to observe pumps’ performance continually. Stations in New York and Boston were sampled for 48-hr periods. Pumps and cassettes were changed after each 8-hr period. One New York station was sampled for 64 hr. About five firefighters were sampled during each 8-hr period. Firefighters in New York and Boston work 8- or 16-hr shifts. Los Angeles work-shifts are 24 hr. For safety and operational reasons, firefighters removed their pumps before leaving the fire station to respond to an alarm. Pumps were taken to an office that was located away from the fire station equipment floor and continued to operate in this area. Upon return to the station, each firefighter started wearing his pump again. During the course of this study, sampling equipment was worn by fire-fighters an average of 6.5 hr per shift. Individual firefighters averaged five alarms of 17 min total duration per alarm. In most cases only one company of five firefighters responded to an alarm, while the second company remained at the station. During the course of this investigation, no large fires kept firefighters away from their stations for extended periods of time, although there were numerous alarms.

Total airborne particulate matter was determined gravimetrically. A time-weighted average (T WA) was determined for each measurement. The methylene chloride soluble fraction was determined as described by Smith. Representative samples were collected at the exhaust pipes of eleven vehicles, five fire trucks and six fire engines in Los Angeles for comparison of the fractional yield of methylene chloride soluble particulates at the point of release with that measured by personal sampling. The vehicles used in Los Angeles, Boston and New York fire departments were all similar. The weight stability of the filters was determined by weighing 17 control (unused) filters at the conclusion of sampling. The average weight change and standard deviation of blanks was 0.001 + 0.001 ug (n = 17).

Sampling was conducted in March and April, 1985, in New York and Boston, and May and June, 1985, in Los Angeles. Because of winter weather conditions, doors and windows of fire stations in New York and Boston were kept closed during the sampling periods except when vehicles were entering or leaving. In Los Angeles it was warmer, and doors and windows usually were left open.

In addition to the assessment of exposure to total particulates under normal operating conditions, the authors also estimated the most severe exposure to diesel particulates that a firefighter might encounter during an 8-hr period in a Los Angeles fire station. To estimate this worst-case scenario, both the truck and engine were turned on and allowed to idle to approximate exposure for the most active day on record of a selected fire station. It was determined that the two fire vehicles would idle for | min per half hour throughout an 8-hr period for a total of 16 min with all the windows and doors in the fire station remaining closed. No fire truck or engine left the station during this simulated exposure. Personal sampling of nine firefighters was conducted over the 8-hr shift to assess individual exposures.

RESULTS

A summary of the measurements of firefighter exposure to total airborne particulates in fire stations in New York, Boston and Los Angeles is found in Table 1. The levels of total airborne particulates ranged from below 100 yg/ m3 to
as high as 480 yg/m3, The table contains both measured levels of total suspended particulates and the number of runs per 8-hr period (runs/ shift). The number of runs is defined as the number of times a vehicle (truck or engine) is turned on and leaves the firehouse. Return to the firehouse is not counted separately.

Figure 1 describes the change in concentration of airborne particulates in a New York fire station as a function of time.
Measurements were made on the main floor (apparatus parking area) with a continuous reading aerosol monitor (RAM-I, GCA Inc.) The direct reading aerosol monitor was placed between the truck and engine near the front of the vehicles. An initial background measurement in the station taken during an inactive period was approximately 40 pg/m3 (measurement made on the main floor as described above). Three vehicles were in the station: a fire engine, a hook and ladder truck, and a chief’s car (van).

Three important sources of particulates beyond those produced by the diesel-powered vehicles were cooking fumes, ambient aerosol and cigarette smoke. All fire station stoves had hoods, with the exception of one in New York. In New York, where more sampling was conducted than elsewhere, cooking meals was found to result in minimal contribution of particulates to the ambient environment. With the exception of the New York fire station without a stove hood, no detectable increase in particulate levels as measured by an aerosol monitor (RAM-I, GCA Inc.) was noted during meals. Thus, this source of particulates was not significant in terms of the overall concentration of particulates,

Outdoor measurements, with the RAM-1, in New York and Boston yielded particulate concentrations between 30 and 60 ug/m3, whereas measured outdoor background in Los Angeles ranged from 30 to 120 ug/m3.

Fourteen percent of the firefighters sampled were smokers. Smokers averaged 62.6 ug/m3 more total airborne particulates than their nonsmoking counterparts. No attempt was made to assess the contribution from side-stream smoking.

Determination of the methylene chloride fraction was carried out on the same samples measured for total particulates. The yield of the methylene chloride soluble fraction averaged 0.24 + 0.01 (fraction + standard error, n = 33). These measurements were derived from vehicles in all three cities. The yield of methylene chloride extractable material taken directly from the exhaust pipes of fire vehicles in Los Angeles was 0.26 + 0.02 (n = 11) of the measured total particulates.
