## I ,

ASSESSMENT OF FIREFIGHTER EXPOSURE TO HCFC-123 DURING FIREEXTINGUISHER USE IN AIRCRAFf HANGARS

Submitted to: American Padfic Corporation 3770 Howard Hughes Parkway Las Vegas, Nevada 89101



# MERiDIANRFSEARCII,hVC.

May 24, 1993ASSESSMENT OFFIREF1GHTEREXPOSURE TO HCFC-123 DURINGFIRE EXTINGUISHERUSE INAIRCRAFT HANGARS

Submitted to: American Pacific Corporation 3770 HowardHughesParkway Las Vegas, Nevada 89101

Submittedby: MeridianResearch,

### Inc. 1010WayneAvenue, Suite 1220 SilverSpring, MD 20910

May24, 1993ASSESSMENT OFF1REFIGHTER EXPOSURE TO HCFC-123 DURINGFIREEXTINGUISHER USE INAIRCRAFT HANGARS



### I. PURPOSE 

### Under Title IV, Section 612 ofthe Clean Air Act Amendments (CAAA) of 1990, the Environmental Protection Agency (EPA) is required to develop regulations governing the use ofsubstitute materials for ozone-depleting chlorofluorocarbons (CFC's) and halons. The statute requires the replacement, to the maximum extent practicable, ofthese materials with alternatives that reduce the overall risks to humans and the environment. In order to make these determinations, EPA must evaluate the risks potentiallyassociated with exposures ofconsumers, workers, and the general population to alternative compounds. One such alternative to the use ofhalon flre extinguishing agent is Halotron I, which contains HCFC-123 (2.2-dichloro-1,1,1-trifluoroethane) as the primary active ingredient. Recently, concerns regarding the potential toxicity ofHCFC-123 and associated risks to exposed workers have arisen from the results ofanimal toxicity testing; in response to these fmdings, the El. 

### duPont deNemours Co., the sole U.S. manufacturer ofHCFC-123, recommended that exposures to HCFC-123 not exceed 10 parts per million (ppm) parts ofair 

### as an 8-hour time-weighted average (TWA), 1,000 ppmfor 30-minute exposures, or 2,500 ppm for 1minute exposures. In a previous evaluation performed for EPA, Meridian Research used a generalized air 

### dilution model to estimate the potential exposure offirefighters to HCFC-123 that may result from using Halotron I extinguishers in aircraft hangars. The results from the model suggested that peak exposures could be as much as 30 times above the 1,000 ppm short-term limit for HCFC-123; however, predicted exposures obtained from the model were associated with a high degree ofuncertainty due to the large range in plausible values for several key variables used in the model. To obtain better information on the potential risks to frreflghter associated with exposure to HCFC-123, Meridian conducted an industrial hygiene survey to measure actual exposures

1that result from using Halotron I in indoor fire situations. In addition, the performance ofthe model previously used by Meridian was evaluated with respect to the exposure monitoring results obtained. The survey was conducted on January 6 and 7, 1993, and
was snonsored bv American Pacific Corporation, which manufactures Halotron I.

----,.---**~** ..... -


### II. DESCRIPTION OFTHE FACILITYAND METHODS USED The surveywas conducted in a typical military aircraft hangar located at the Charleston Air Force Base in South Carolina. The hangar measured approximately210 feet long by90 feet wide by50 feet high atits peak, and was vacant at the time ofthe survey. According to Air Force personnel, this hangar is considered to be small compared to most installations world-wide. The hangar was equipped with a series of manually operated baydoors that permitted the hangar to be opened on one side along its entire length. Smaller baydoors were present along the opposite side; these were partiallyopen during all tests conducted. There were no forced ventilation systems available for use in this hangar. A trained frrefighter operated all frre extinguisher equipment,which consisted of hand-held 20-pound units and portable 150-pound units filled to capacitywith the Halotron I agent. During the tests, the frrefighter wore a complete ensemble of protective gear, including a self-contained breathing apparatus (SCBA). The extinguisher units were completelydischarged for each test. A series offive tests were conducted
over a two-dayperiod. On the frrst day, a 20-pound unit and a 150-pound unit were discharged with the large bay doors closed. On the second day, a 20-pound unit was tested with the large baydoors closed, after which the large bay doors were open while conducting one test each with a 150- and 20-pound unit. Typically, the bay doors will be open when aircraft and personnel are working in the hangar. Exposure of the frrefighter to HCFC-123 was evaluated bycollecting air samples in 1-liter Tedlarbags during discharge ofeach extinguisher unit." A standard sampling cassette holder equipped with a halfcassette was attached near the frrefighter's breathing
zone and outside ofthe protective hood. Tygon tubing was used to connect the cassette holder to the air inlet ofan SKC Model 224 personal sampling pump, and from the



### 2exhaust port ofthe pump to the Tedlar bag. The flow rate ofthe pump was set between 0.75 liter per minute and 1.75 liters per minute, depending on the expected duration of Halotron I discharge. Collection ofair was ceased as soon as possible after completion

To evaluate potential exposures ofpersonnel entering the hangar after a flre event, and to provide data that could be used to evaluate the performance ofthe theoretical model, a series ofstationary area sampling devices were set up atvarious points along the length ofthe hangar. The configuration ofthe hangar and approximate location ofthe flreflghter and area samples are shown in Figure 1. Area samples were collected on SKC 50/100 mg charcoal tubes using a flow rate of50 

### eelmin; for each sample, two charcoal tubes were used in series to minimize sample loss due to breakthrough. With the exception ofone test, area samples were collected over 30- minute periods; a 15-minute sampling duration at twice the normal flow rate was used for the test ofthe 20-pound unit with the large bay doors open. The limit ofdetection for HCFC-123 using these methods was 1ppm. A portable MIRAN-1BX Ambient Air Analyzer (Foxboro) was used to obtain periodic real-time measurements of HCFC-123 concentrations during each test. This instrument was pre-calibrated for HCFC-123, and had a working range of 1.9 to 1,000 ppm. The MIRAN was used to verify that concentrations ofHCFC-123 at various locations in the hangar had fallen to below detectable levels before starting a new test. Results obtained from the Miran will differ from those obtained from the area samplers because the area samplers yield an average HCFC-123 concentration over the sampling period, whereas the Miran measures the HCFC-123 concentration at a given point in time. The Tedlar bag and charcoal tube samples were analyzed using gas chromatographyby a laboratory accredited by the American Industrial Hygiene Association (Gascoyne Laboratories,Inc., Baltimore, Maryland). Charcoal tube samples
were desorbed with carbon disulflde prior to analysis. For the Tedlar bag samples, the column used by Gascoyne was 5 percent Krytrox 143 AC on Graphpac GB with a 60/80 mesh that was 10 feet by 1/8 inch SS and had a flow of30 ml/minute (helium). The

3following GC conditions were noted: injection temperature 22SOC; detector temperature 250'C; a run time of 16 minutes; and an oven temperature of70'C (isothermal). A Perkins-Elmer gas chromatograph with a sigma lB analyzer equipped with a flame ionization detector (FID) and a sigma lB integrator/GC control was used for analysis. Injections were done with a gas-tight syringe. To examine the stability of HCFC-123 in Tedlarbags, Gascoyne performed a decay rate study using 10, 100, and 1000 ppm concentrations ofHCFC-123 spiked into Tedlar bags. The spiked samples were held at room temperature and alloquats were withdrawn for analysis at various intervals over a 3-dayperiod. The results ofthis decay rate study are shown in Attachment 1, and demonstrate that there was no significant sample loss over the 3-daytest period.



### m. RESULTS AND DISCUSSION Tables 1 and 2 show the results obtained from the MIRAN analyzer and charcoal tubes, respectively. HCFC-123 concentrations exceeded 1,000 ppm only following the test ofthe 150-pound unit with the large bay doors closed; concentrations fell to below 1,000 ppm within 30 minutes after agent discharge. Natural air ventilation provided by the two small, partially open bay doors was sufficient to reduce HCFC-123 concentrations to below 10 ppmwithin two to three hours. Table 3 provides the results from personal breathing zone air sampling conducted using the Tedlarbags. Exposure ofthe firefighter to HCFC-123 during agent discharge
was well below 1,000 ppm for all test trials. On the second day oftesting, there was an appreciable air flow from the smaller bay doors towards the large bay doors; this caused the visible cloud ofextinguishant material to move directly towards the flreflghter when the large bay doors were open. As a result, the exposure ofthe firefighter to HCFC-123
was generally higher during the two tests conducted with the large bay doors open. The measured exposure of the firefighter to HCFC-123 was substantiallybelow the values previously predicted by Meridian using the general air dilution model. The model that was used in the prior analysis for EPA is derived from a differential material balance that, when integrated, provides a basis for relating airconcentration of

4contaminant to the generation and removal rates ofa contaminant. Starting with a fundamental material balance equation, assuming no contaminant is in the supply air:

Rate ofAccumulation = Rate ofGeneration

- Rate ofRemoval
VdC=Gdt-Q'Cdt (Equation3-1)
Where: C = Concentration ofgas or vapor at time t G = Rate ofgeneration ofthe contaminant (cfm) Q' = Effective rate ofventilation that is corrected for incomplete mixing (cfm) (a mixing factor of

### 05 is assumed, which is multiplied by the actual ventilation rate to yield Q') V = Volume ofroom or enclosure (ff) Rearranging,integrating, and further simplifying the material balance equation yields the fmal equation used to estimate contaminant concentration during the release ofthe contaminant, assuming that there is no initial concentration at time = 0:

(Equation3-5)

When the release ofcontaminant stops, the air concentration declines as the contaminant is diluted by fresh air. That is:

Rate ofAccumulation = Rate ofRemoval VdC=-Q'Cdt (Equation3-6) Rearranging, integrating, and further simplifying this material balance equation results in the equation used to estimate contaminant concentration after a given period ofdilution:
5(Equation3-7)

(Equation3-8)
(Equation3-9) 

### _.2:(t-t] C =C e v**-~** '·

2 1 (Equation3-10) 

### The area sampling data obtained during this survey now provides the information needed to explore the reasons underlying the model's tendency to overestimate exposures offrrefighters using Halotron I in 

### large, enclosed areas. To perform this analysis, Meridian defmed the boundaries ofan imaginary ''box" in 

### which the frrefighter was stationed during the discharge ofthe Halotron I agent. The boundaries ofthe floor area ofthe box are defined bythe locations ofthe area sampling stations on either side ofthe firefighter, i.e., the area samplers at locations 1 and 2 in 

### Figure 1. 

### The forward end of the boxis defmed by the hangar wall, and the back end ofthe box is defined by the frrefighter's location during agent discharge. The floor area for this defined space is approximately 3,800 ft_l. Meridian also assumed an effective height ofthe imaginarybox of 12 feet, the same as assumed in 

### the prior analysis conducted for EPA; thus, the total volume ofthe imaginary box is about45,000 ff. Using the model described above and the volume ofthe defined box, Meridian estimated the HCFC-123 concentrations that
are predicted to result at air 

### exchange rates of3, 10, or 30 air 

### changes perhour (ACH) (air 

### exchange rates were selected to be consistent with the previous analysis conducted for EPA). The results ofthe model runs are compared to the average HCFC-123 concentrations measured at area sample locations 1and 2; Table 4 contains the results ofthe model runs as compared to actual measured HCFC-123 concentrations. Under the conditions ofthese tests, the predictive model failed to adequately describe the actual concentrations ofHCFC-123 found in the immediate vicinity ofagent discharge. At lower air 

### exchange rates (i.e., 3 and 10 ACH), predicted HCFC-123
6

### concentrations were substantially higher than actual measured concentrations. At an air 

### exchange rate of30 ACH, the concentration predicted to result shortly after agent discharge is 

### within a factor oftwo times the measured concentration; however, the model predicts that the decline in HCFC-123 concentration is much faster than the decline 

### measured by the area samplers. Thus, the actual average air 

### exchange rate in this 

### area ofthe hangar appeared to be well below 30 ACH. The comparison between predicted and measured concentrations is the same for both trials involving the 20-pound and 150- pound units. The inability ofthe model to accurately predict HCFC-123 concentrations under the test conditions most likely reflects a violation ofthe basic assumption underlying the model that a contaminant, once released, immediatelyfills the space defined by the box. The violation ofthis assumption was visually apparent during the test, in which a portion ofthe visible cloud ofextinguishing agent could be observed moving away outside ofthe region ofthe imaginarybox in which the firefighter was stationed. In addition, the extinguishing agent is forcefully discharged away from the frrefighter at a distance of about 10 feet; thus, a large portion ofthe material never reaches the immediate vicinity ofthe firefighter, resulting in exposures that are lower than predicted by the model. Thus, the heterogeneous dispersion ofthe extinguishing agent rendered the boundary definition ofthe imaginaryboxinaccurate. The results ofthe monitoring survey and the comparative analysis described above indicate that the model previously used by Meridian is not suitable for predicting exposures offrrefighters using extinguishing agents in relatively large spaces. Comparison ofthe monitoring results with DuPont's allowable exposure limits of 1,000 ppm for 30 minutes and 2,500 ppm for one minute indicates that, under the conditions ofthese tests, use ofHalotron I extinguishing agent in aircraft hangars appears to be safe from the perspective ofworker health.

7

# Figure 1.**(~onfi_guration ofHan~ar** 

# andLocationof ]Firefighterand

# Area 3amplers

······················· 

## l Office 1 

# j 4 PartiallyOpen BayBoor Half-Open BayDoor



## 3 2 Closed BayDoor

# I Directionof AgentDischargl

# ~·**~**

# ~/ FF

LocationofAreaSamplingPumps
LargeBayDoors

### Table L HCFC-123 Concentrations Measured withthe MiranAnalyzer
AverageConcentration (QQm) in Locationa: TimeAfter Discharge Discharge(min) 1 Point 2 3 Testof20-4b. unit,Day 1 15 140**21~50** 46 19 40 18 20 13 13 90 4.5 4.0 3.1 4.0 120 2.5 3.1 2.0 2.1 Testof 15D-lb. unit,Day 1 30 700 1000 700 700 60 145 180 120 9 10 11 9.5 170 3.2 4.4 

### 5.0 4.0 Testof20-4b. unit,Day 2 

### 5**20~00** 400-500 360 10Q-500 20 40 39 34 28 45 6.5 6.7 6.6 6 80 <1.9 <1.9 <1.9 <1.9 Testof 150-4b. unit,Day2 b 5 100 120 210 150 15 15 16 17 19 30 1.3 2.0 2.8 3.2 Testof20-4b. unit,Day2 b 5 41 45 45 15-20 15 4.2 4.3 5.3 5.2

a Numerical designationscorrespondtolocations showninFigure 1. bLargebaydoors wereopenfor testsconductedonDay 2. 4

29 12 3.7 2.1

650 180

7 2.5

630

37 3.5 <1.9

23Q-250 35 3.6

4-6 5.6

### Table4. Comparison ofMeasured andPredicted HCFC-123 Concentrations

PredictedHCFC-123 Cooncentration TimeAfter Measured HCFC-123 atDesignatedAirExchangeRate(ACH) Discharge(min) Concentration(ppm) 3 10 30 Testof2o-l.b. unit,Day 1 

### <HO 68.5 656.0 321.0 983 3o-60 13.8 307.0 25.8 .05 60-90 5.6 144.0 2.1 <01 90-120 23 67.7 0.2 <01 12Q-150 1.1 31.8 <.01 <01 Testof 15o-l.b. unit,Day 1 

### <HO 471.2 4,913.0 2,408.0 737.0 3o-60 245.4 2,306.0 193.0 0.4 60-90 73.7 1,082.0 15.5 <01 90-120 27.1 508.0 13 <.01 12G-150 9.45 238.0 0.1 <01 15Q-180 6.85 112.0 <01 <01

1?ATI'ACHMENT I

# @a:s.cn~n.e 

# 'lfiahnra±uri.e:s,**~n.c~**

· Baltimore, MD 21224**~m©?~w~** {410) 633-1800 FAX NO. {410) 633·6553 {8001 GAS·COYN Report No. 92-10-487 Report Date: November 19, 1992 Report To: Meridian Research Page:. 2 of 4 Decay Rate Study of Laboratory Prepared HCFC-123 in 

### Air Samples Theoretical Value 

## = 8.9 ppm Theoretical Value 

# = 89 ppm Theoretical Value = 890 ppm Elapsed Time 

### o hours 8 hours 24 hours 32 hours 48 hours 72 hours

Notes: 7.7, 7.7 76, 82 1100, 1100 7.5, 7.5 80, 78 940, 950 

### .a.o, 8.2 79, 100 1000, 1000 8.6' 9.5 120, 91 1000, 1000 8.4, 8.2 84, 91 1000, 1000 8.7, 8.0 100, 125 900, 920

(1) Results are expressed in parts per million (ppm). (2) Duplicate analyses are reported for each time period. (3) Analysis performed with parameters outlined in method submitted to Gascoyne Laboratories, Inc. by Meridian Research. (4) All analyses were performed 

### ± 1 hour of target analysis time. (5) Analyst(s): JMRfSJN; Date Test Completed: 11/06/92

### ~- William L. Lock Laboratory Director