Occupational Health Chemistry - ACS Publications - American

10 Occupational Health Chemistry Collection and Analysis of Airborne Contaminants ROBERT C. VOBORSKY

Downloaded by UNIV OF ARIZONA on January 13, 2013 | http://pubs.acs.org Publication Date: April 22, 1980 | doi: 10.1021/bk-1980-0120.ch010

Sentry Insurance, 1800 North Point Drive, Stevens Point, WI 54481

At no time i n modern history has the general public been more conscious of health and environmental issues. Therefore, it is somewhat understandable that we have witnessed, i n just a very few years, the enactment of more federal l e g i s l a t i o n i n occupational and environmental health than has been legislated i n the history of this country, or any other nation. However, this has been achieved during a period of general national unrest induced by many s o c i a l , economic and political factors. The state of one's health is determined by heredi t a r y factors and the quality of the total environment. The l a t t e r involves the home, community, work place and recreational pursuits, for the conditions in each can present health problems. The employee spends only one- t h i r d of his day in the work place and the remaining time i n a home, community and recreational environments. The great achievement of our modern technology must now be paralleled by equal progress i n our knowledge of the effects of waste products of this technology upon man's health and the application of this technology to control programs. The chemical substances which can characterize the work environment consist of dust, fumes, vapors, gases and mists. The determination of the quality of the work place requires r e l i a b l e monitoring programs. Accordingly, standards are established within which quality determinations must comply. Industry i s i n the age of compliance. In environmental or occupational health, regulatory agencies establish standards by which Industry must comply. Such health standards have been promulgated by the Occupational Safety and Health Administration (OSHA) under the authority granted under the Federal Occupational Safety and Health Act of 1970. Therefore, data derived from competent i n d u s t r i a l hygiene tests i s the determinant of compliance with health standards involving chemical agents. Industrial hygiene monitor0-8412-0539-6/80/47-120-185$05.00/0 © 1980 American Chemical Society In Analytical Techniques in Occupational Health Chemistry; Dollberg, D., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1980.


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ing programs are a l s o of major s i g n i f i c a n c e i n determining the e f f e c t i v e n e s s or e f f i c i e n c y of engineering measures f o r c o n t r o l l i n g hazards or p o t e n t i a l exposures to chemical agents. The most important value of the data derived from monitoring the work environment i s the c o r r e l a t i o n of such information with medical and b i o l o g i c a l t e s t data obtained through examination of the worker. Such c o r r e l a t i o n i s the f i n a l t e s t of the s a f e t y of the q u a l i t y w i t h i n the work environment. The Occupational Safety and Health Act of 1970 e s t a b l i s h e d the N a t i o n a l I n s t i t u t e f o r Occupational Safety and Health (NIOSH) w i t h i n the Department of Health, Education and Welfare. NIOSH i s p r i m a r i l y f o r the purpose of c a r r y i n g out the research and educat i o n a l f u n c t i o n s of the Act. The f u n c t i o n s of NIOSH include the research programs aimed at i d e n t i f y i n g and e v a l u a t i n g hazards i n the work environment. In the e v a l u a t i o n of h e a l t h hazards from t o x i c and carcinogenic a i r contaminants, the sampling and a n a l y t i c a l method i s a very important t o o l . NIOSH has researched the sampling and a n a l y s i s of over 400 airborne substances which are c a t e g o r i z e d as dusts, fumes, vapors, gases and mists. By adhering to these sampling and a n a l y t i c a l methods, which are e s t a b l i s h e d f o r use by i n d u s t r i a l h y g i e n i s t s i n the f i e l d and i n the l a b o r a t o r y , a r e l i able and competent assessment of the work environment w i l l result. Dust Dust i n the work p l a c e i s present i n v a r y i n g s i z e s and shapes depending on the process. G e n e r a l l y , the dust which i s seen by the human eye i s greater than 50 microns. The dust which i s capable of e n t e r i n g the upper r e s p i r a t o r y system and e v e n t u a l l y the inner most s e c t i o n s of the lung are l e s s than 10 microns i n s i z e . The r e s p i r a b l e f r a c t i o n of dust i s that p o r t i o n of airborne p a r t i c u l a t e matter which i s l e s s than 10 microns. R e s p i r a b l e dust g e n e r a l l y remains i n the work p l a c e atmosphere f o r long periods of time when v e n t i l a t i o n systems are not e f f i c i e n t or are not present at all. In order f o r a l e g i t i m a t e assessment of a dust exposure, the r e s p i r a b l e f r a c t i o n of the dust must be c o l l e c t e d and evaluated. This task i s achieved by using a 10 m i l l i m e t e r nylon cyclone. FIGURE 1 i l l u s t r a t e s the cyclone, and TABLE 1 l i s t s the c o l l e c t i o n e f f i c i e n c y of the cyclone which i s operated at a very c r i t i c a l flow rate of 1.7 l i t e r s of a i r per minute. The flow r a t e i s a c c u r a t e l y c a l i b r a t e d to w i t h i n ±5% by using the c a l i b r a t i o n t r a i n i l l u s t r a t e d i n FIGURE 2. The f i l t e r holder, c o n t a i n i n g a 37 mm diameter, 5.0 micron pore s i z e hydrophobic p o l y v i n y l c h l o r i d e f i l t e r ,

In Analytical Techniques in Occupational Health Chemistry; Dollberg, D., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1980.

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187

TABLE 1

COLLECTION EFFICIENCY OF 10MM


Size (Microns)

2.0 2.5 3.5 5.0 10.0

CYCLONE

% Passing S e l e c t o r (1.70 LPM)

90 75 50 25 0

which has been preweighed to the nearest 0.01 m i l l i g r a m i s attached s e c u r e l y to the cyclone p r i o r to c a l i b r a t i o n . A minimum sampling p e r i o d of 60 minutes i s recommended and longer periods of up to e i g h t hours are p r e f e r a b l e . The amount of p a r t i c u l a t e c o l l e c t e d on the f i l t e r i s determined by weighing the f i l t e r under the same p h y s i c a l c o n d i t i o n s as p r i o r to sampling. The amount of p a r t i c u l a t e with respect to t o t a l sampling time and flow rate determines the dust c o n c e n t r a t i o n i n m i l l i g r a m s per cubic meter (mg/M ). The current OSHA Threshold L i m i | Value f o r nuisance or i n e r t r e s p i r a b l e dust i s 5 mg/M . Monitoring dust atmospheres which are suspected of c o n t a i n i n g f r e e s i l i c a , the f i l t e r c o n t a i n i n g the r e s p i r a b l e f r a c t i o n of the dust i s analyzed f o r s i l i c a content. Three a n a l y t i c a l methods are c u r r e n t l y used for s i l i c a determination. The f i l t e r media can be destroyed and the remaining m a t e r i a l re-deposited on a s i l v e r membrane f i l t e r and analyzed by X-Ray D i f f r a c t i o n or the remaining m a t e r i a l can be p e l l e t i z e d with potassium bromide and analyzed with a scanning I n f r a r e d Spectrophotometer with a peak r e s u l t i n g at the 800 cm line. The t h i r d method developed by T a l v i t i e , i s the c o l o r i m e t r i c determination of s i l i c a as molybdenum blue at 820 nm's. The s i l i c a , or o< quartz content i s reported as a percent of the dust c o l l e c t e d of the f i l t e r , and a r e p r e s e n t a t i v e t h r e s h o l d l i m i t value i s c a l c u l a t e d by the f o l l o w i n g r e l a t i o n s h i p :

S i l i c a dust can be present i n i n d u s t r i a l atmospheres i n three forms, quartz, c r i s t o b a l i t e and t r i d y m i t e , depending upon the process temperatures. When c r i s t o b a l i t e or t r i d y m i t e are present, one-half the value of the t h r e s h o l d l i m i t formula i s used. The v a l i d i t y of the r e s u l t s depends on the cyclone and pump system


188

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to Pump

5u Polyvinyl Chloride Filter (Respirable Fraction) 2 pc. Cassette Total Dust Inlet (1.70 LPM)


Figure 1. 10-mm nylon cyclone collec tion system

Grit Pot (Non Respirable Fraction)

I

Tubing

Cyclone Soapbubble Meter

Personal Sampling Pump Sealed Container

u

Manometer (water)

e Figure 2.

Soap Solution

Calibration setup for personal sampling pump with cyclone collection system

- Tubing

2 pc. Cassette Soapbubble Meter

Personal Sampling Pump

U

Manometer (water)

Beaker

Figure 3.

Β

Soap Solution

Calibration setup for personal sampling pump with filter cassette


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c a l i b r a t i o n and the p r e c i s i o n and accuracy o f the a n a l y t i c a l method used f o r the s i l i c a determination.


Metal Fume Metal fumes i n the work p l a c e are generated by heating metal to a high enough temperature to produce fume which i s g e n e r a l l y i n the oxide s t a t e . Exposures to metal fume are formed during welding, s o l d e r i n g , smelting, r e f i n i n g , heat t r e a t i n g and f i n i s h i n g operat i o n s . The metal of i n t e r e s t i s dependant on the m e t a l l u r g i c a l composition of the raw ore process materi a l s or a l l o y being processed. C o l l e c t i o n o f metal fume i s accomplished by passing the contaminated a i r through a f i l t e r holder c o n t a i n i n g a 37 m i l l i m e t e r , 0.8 micron mixed c e l l u l o s e e s t e r membrane f i l t e r supported by a c e l l u l o s e backup pad. A p o r t a b l e pump and f i l t e r system i s c a l i b r a t e d f o r a flow rate o f 1.5 l i t e r s o f a i r per minute, using the c a l i b r a t i o n t r a i n i l l u s t r a t e d i n FIGURE 3. The accuracy of the c a l i b r a t i o n must be w i t h i n ± 5%. A samp l i n g p e r i o d o f one hour i s recommended, and longer periods o f time are p r e f e r a b l e . Since i t i s p o s s i b l e f o r the f i l t e r to become plugged by heavy p a r t i c u l a t e loading or by the presence of o i l mist or other l i q u i d s i n the a i r , the pump rotameter should be observed f r e q u e n t l y and readjusted a c c o r d i n g l y . The metal fume f i l t e r samples are prepared f o r a n a l y s i s by d e s t r o y i n g the organic f i l t e r media by heating with r e d i s t i l l e d n i t r i c a c i d on a hot p l a t e . The r e s u l t i n g metal, i n the s a l t s t a t e , i s d i s s o l v e d i n n i t r i c a c i d and d i l u t e d to a known volume with double d i s t i l l e d water. The s o l u t i o n i s analyzed by Atomic Absorption f o r the metals o f i n t e r e s t . Metals such as Cadmium, Berylium and N i c k e l have very low t h r e s h o l d l i m i t values which are set by OSHA and are f r e q u e n t l y present i n the sample i n very low q u a n t i t i e s . Many Atomic Absorption u n i t s are equipped with a hollow graphite tube atomizer which increases the s e n s i t i v i t y d r a m a t i c a l l y making i t e a s i e r f o r the a n a l y s t to o b t a i n r e l i a b l e r e s u l t s f o r species present i n the sample i n very low c o n c e n t r a t i o n s . The v a l i d i t y o f the metal fume data depends on sampling t r a i n c a l i b r a t i o n and the p r e c i s i o n and accuracy o f the a n a l y t i c a l procedure. NIOSH has reported a 2% r e l a t i v e standard d e v i a t i o n i n the a n a l y t i c a l method which has been c o l l a b o r a t i v e l y tested. Organic Vapors Organic vapors are generated i n the work p l a c e wherever organic solvents are used. The q u a n t i t y o f



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organic vapors present depends on the process tem perature, vapor pressure of the solvent and e f f i c i e n c y of exposure c o n t r o l equipment. Examples of exposures to organic vapors are evident during p a i n t i n g , c l e a n i n g and degreasing and those operations i n v o l v i n g adhesives. Organic vapors are e a s i l y c o l l e c t e d by passing the contaminated a i r at a flow rate of 50,100 or 200 cubic centimeters per minute through a small tube c o n t a i n i n g a c t i v a t e d c h a r c o a l . FIGURE 4 i l l u s t r a t e s the components of a charcoal tube prepared according to NIOSH s p e c i f i c a t i o n s . The tube i s l i m i t e d to sample volumes of 10 l i t e r s of a i r and can vary depending upon the contami nant's chemical c h a r a c t e r i s t i c s . Most a l l organic vapors are c o l l e c t e d on a c t i v a t e d c h a r c o a l , although the c o l l e c t i o n e f f i c i e n c y f o r aromatic amines and s t r a i g h t chain amines are g r e a t l y increased when tubes prepared with alumina and s i l i c a g e l are employed. Because of the flow rate i n v o l v e d i n sample c o l l e c t i o n , a p o r t a b l e pump designed f o r use a t low flow rates i s recommended. Many pumps on the market are equipped with a d i g i t a l counter which a c c u r a t e l y i n t e grates the volume of a i r sampled. C a l i b r a t i n g the sampling pump i s very important i n t h i s monitoring procedure. FIGURE 5 i l l u s t r a t e s a c o r r e c t method f o r a c c u r a t e l y determining the flow rate of a t y p i c a l low flow c o l l e c t i o n system. The c o l l e c t i o n tubes are prepared f o r a n a l y s i s using d i s t i l l e d carbon d i s u l f i d e as a desorbing agent. The d e s o r p t i o n phase i s u s u a l l y complete w i t h i n t h i r t y minutes. The carbon d i s u l f i d e s o l u t i o n i s then analyzed by a Gas Chromatograph equipped with a flame i o n i z a t i o n detector. The s e p a r a t i o n column s p e c i f i e d by NIOSH i s a 20 f t . χ 1/8 i n . s t a i n l e s s s t e e l column packed with 10% FFAP on Chromosorb W. A l t e r n a t i v e columns, such as 10% SE-30 on Chromosorb W or Porapak Q can be used depending on s e p a r a t i o n and peak r e s o l v i n g problems. The p r e c i s i o n and accuracy of the a n a l y t i c a l methods depends s t r o n g l y on the d e s o r p t i o n e f f i c i e n c y which i s the percent removal of contaminent from the c o l l e c t i o n media. An E l e c t r o n Capture d e t e c t o r w i l l d e f i n i t e l y increase the accuracy of c h l o r i n a t e d s p e c i e s . P r e c i s i o n i s increased by using the s o l v e n t f l u s h technique of sample i n j e c t i o n . Organic Vapors may a l s o be c o l l e c t e d i n T e d l a r , Mylar, or Saran bags. A drawback to t h i s procedure i s that the sample must be analyzed as soon as p o s s i b l e because of sample l o s s through the bag or by absorbing to the i n n e r w a l l s of the bag. Samples c o l l e c t e d on a c t i v a t e d charcoal can be r e f r i g e r a t e d f o r extended periods of time p r i o r to d e s o r p t i o n . Research i n the area of long-term storage has revealed that the organic species c o l l e c t e d tend to d r i f t and e q u i l i b r a t e i n both


Analysis


VOBORSKY

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191

Contaminants

2 0 - 4 0 MESH ACTIVATED COCONUT CHARCOAL

Figure 4.

Charcoal tube sampling device

Tubing

Soap Bubble Meter (inverted buret) Charcoal Tube

5ÔÔ

t

Personal Samplmg Pump

1QQQJ Beaker soap solution

water manometer

Figure 5.

Calibration setup for personal sampling pump with charcoal tube


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the sample s e c t i o n and backup s e c t i o n s of the tube.


O i l Mist O i l mist i s a very common airborne contaminant i n work p l a c e atmospheres where process machinery i s cooled or l u b r i c a t e d with i n d u s t r i a l grade l u b r i c a n t s . O i l mist i s c o l l e c t e d by drawing a known volume of contaminated a i r through a c e l l u l o s e membrane f i l t e r at a flow rate of 1.5 l i t e r s of a i r per minute to trap the p a r t i c u l a t e o i l mist present. The sampling t r a i n i s c a l i b r a t e d i n the same manner as discussed i n the metal fume c o l l e c t i o n procedure (see FIGURE 3). A sample s i z e of 100 l i t e r s i s recommended, although longer samples are p r e f e r r e d . Since i t i s p o s s i b l e f o r the f i l t e r to become plugged by heavy p a r t i c u l a t e o i l loading, the pump rotameter should be observed f r e quently and readjusted as needed to insure an accurate sample volume. The f i l t e r i s prepared f o r a n a l y s i s by e x t r a c t i n g the organic l u b r i c a n t s with d i s t i l l e d reagent grade chloroform. P r i o r to a n a l y s i s by fluorescense spectrophotometry, a bulk sample of the l u b r i c a n t used i n the work p l a c e during sample c o l l e c t i o n i s scanned i n order to s e l e c t the proper e x c i t a t i o n and emission wavelengths. Standards are prepared from the bulk l u b r i c a n t , and the f i e l d samples are then analyzed at the predetermined wavelengths. Samples c o n t a i n i n g graphite dust or other i n e r t p a r t i c u l a t e can be f i l t e r e d or c e n t r i f u g e d p r i o r to a n a l y s i s i n order to o b t a i n maximum emission. Inorganic Gases I n d u s t r i a l process gases and by-products such as Ammonia, S u l f u r Dioxide, Hydrogen S u l f i d e , Nitrogen Dioxide, Hydrogen Cyanide and Hydrogen F l u o r i d e are present i n many i n d u s t r i a l s i t u a t i o n s . The gases d e s c r i b e d can be e a s i l y c o l l e c t e d by drawing the contaminated a i r through a midget impinger c o n t a i n i n g 10 m i l l i l i t e r s of absorbing s o l u t i o n . The c o l l e c t i o n system i s g e n e r a l l y c a l i b r a t e d f o r flow rates of 1.0-2.0 l i t e r s of a i r per minute. A 100 - 150 l i t e r a i r sample i s s u f f i c i e n t f o r the d e t e c t i o n and measurement of most gases encountered i n i n d u s t r i a l situations. The absorbing s o l u t i o n s are analyzed e i t h e r by s p e c i f i c i o n e l e c t r o d e , c o l o r i m e t r y , or t i t r a t i o n depending on the analyte of i n t e r e s t . TABLE 2 presents a l i s t of absorbing s o l u t i o n s and method of a n a l y s i s f o r a v a r i e t y of gaseous a i r contaminants. The o v e r a l l p r e c i s i o n and accuracy of the method depends on c a l i b r a t i o n , a b s o r p t i o n e f f i c i e n c y , i n t e r f e r e n c e s present and time d u r a t i o n between c o l l e c t i o n and a n a l y s i s .


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TABLE 2 IMPINGER SAMPLING GAS


Hydrogen Cyanide S u l f u r Dioxide Hydrogen S u l f i d e Nitrogen Dioxide Hydrogen F l u o r i d e Ammonia

ABSORBING SOLUTION Sodium Hydroxide Hydrogen Peroxide Cadmium Hydroxide S u l f a n i l i c Acid Sodium Hydroxide S u l f u r i c Acid

ANALYSIS Ion S p e c i f i c E l e c t r o d e Titration Colorimetric Colorimetric Ion S p e c i f i c E l e c t r o d e Ion S p e c i f i c E l e c t r o d e

An a l t e r n a t i v e to the impinger c o l l e c t i o n method i s the use of c o l o r i m e t r i c i n d i c a t i n g tubes. A s p e c i f i c volume of contaminated a i r i s drawn through a tube c o n t a i n i n g r e a c t i v e chemicals which r e l a t e s the concent r a t i o n to the length of c o l o r s t a i n produced. Originally, the i n d i c a t i n g tubes were prepared and c a l i b r a t e d f o r spot checking which would not give a time i n d i c a t i o n of the time-weighted average concentration unless m u l t i p l e samples were taken. Recently, the major tube manufact u r e r s have c a l i b r a t e d a v a r i e t y of i n d i c a t i n g tubes which can be used i n conjunction with low flow pumps r e s u l t i n g i n a time-weighted average reading f o r an e n t i r e work s h i f t . D i r e c t - r e a d i n g f i e l d monitors equipped with chart recorders are a l s o a v a i l a b l e f o r monitoring many indust r i a l gases over long p e r i o d s of time i n order that an accurate time-weighted average concentration can be produced. Many manufacturing f a c i l i t i e s have permanently i n s t a l l e d a i r contaminant monitors equipped with alarms which sound when the t h r e s h o l d l i m i t c o n c e n t r a t i o n i s exceeded. Asbestos Asbestos f i b e r s have been proven to produce lung cancer; and t h e r e f o r e , a s t r i c t monitoring requirement has been set f o r t h by OSHA. Monitoring asbestos may tend to be d i f f i c u l t at f i r s t , depending on the i n t e r ference of other p a r t i c u l a t e i n the atmosphere and the volume of a i r sampled. Asbestos samples are c o l l e c t e d by drawing contaminated a i r at a flow rate of 1.5 l i t e r s of a i r per minute through an open-face 37mm f i l t e r holder c o n t a i n i n g an 0.8 micron c e l l u l o s e e s t e r f i l t e r . (The f i l t e r i s housed i n a three-piece f i l t e r holder or c a s s e t t e . P r i o r to sampling, the top p a r t of the cassette i s removed i n order to expose the t o t a l surface area of



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the f i l t e r i n insure uniform p a r t i c u l a t e and f i b e r d e p o s i t i o n . ) The c o l l e c t i o n system i s c a l i b r a t e d i n the same manner as the metal fume system i l l u s t r a t e d i n FIGURE 3. The sampling d u r a t i o n depends on the amount of dust i n the atmosphere to be monitored. G e n e r a l l y , a 15 minute sample i s s u f f i c i e n t f o r a r e l a t i v e l y dustf r e e s i t u a t i o n . The sample i s evaluated by mounting a small " p i e shaped" s e c t i o n of the f i l t e r on a s l i d e using a mounting media prepared by mixing a s p e c i f i e d amount o f f i l t e r m a t e r i a l with equal parts o f dimethyl p t h a l a t e and d i e t h y l oxalate. A microscope equipped with a phase c o n t r a s t o p t i c a l accessory, 10 X o b j e c t i v e s and a c a l i b r a t e d p o r t i o n r e t i c l e i s used f o r counting at 450X. G e n e r a l l y , a count o f 100 f i b e r s g r e a t e r than 5 microns i n length i s s u f f i c i e n t ; and requirements are that a t l e a s t 20 f i e l d s must be counted. When very low concentrations are evident, 100 f i e l d s or 100 f i b e r s , whichever occurs i s the general r u l e o f thumb. An i d e a l count would be 1 to 5 f i b e r s per f i e l d . Asbestos concentrations are reported i n f i b e r s per cubic centimeter which takes i n t o account the f i b e r s counted, area of the f i l t e r , f i e l d area of the p o r t i o n r e t i c l e and the volume o f a i r drawn through the f i l t e r . The primary reason f o r short-term sampling of dusty atmospheres i s b a s i c a l l y t h a t the f i l t e r becomes impregnated with numerous dust p a r t i c l e s and f i b e r s and i s very hard to s u c c e s s f u l l y count under the microscope. Heavy c o n c e n t r a t i o n of p a r t i c u l a t e s hinders the s i z i n g of f i b e r s . F i b e r s may be p a r t i a l l y or e n t i r e l y obscured from view. C e r t a i n counting r u l e s must be followed i n order to achieve an accurate and s t a t i s t i c a l l y s i g n i f i c a n t count. These r u l e s i n c l u d e r e c o g n i z i n g , s i z i n g and counting o f f i b e r s and proper use o f the boundaries o f the p o r t i o n r e t i c l e . NIOSH has c o l l a b o r a t i v e l y t e s t e d the f i b e r counting procedure and has observed a s t a t i s t i c a l counting e r r o r no g r e a t e r than 20%.


10.

VOBORSKY

Analysis

of Airborne

Contaminants

195

BIBLIOGRAPHIC REFERENCES U. S. Department of Health, Education and Welfare, "NIOSH Manual of Analytical Methods," 2nd Edition, Vol. I., II., III., Cincinnati: Public Health Service, 1977. U. S. Department of Health, Education and Welfare, "NIOSH Manual of Sampling Data Sheets," 1977 Edition, Cincinnatti: Public Health Service, 1977.


Leithe, Wolfgang, "The Analysis of Air Pollutants," Ann Arbor: Ann Arbor Humphrey Science Publishers, 1970. Leichwitz, K. R., "Detector Tubes and Prolonged Air Sampling," National Safety News, April, 1977. "Industrial Hygiene Manual," Supplement 109, Occupational Safety and Health Reporter, Bureau of National Affairs, Inc., Washington, D.C., June 16, 1977. "Environmental Health Monitoring Manual," U.S. Steel Corp., Birmingham, Alabama, 1973. Orion Research: "Analytical Methods Guide," Sixth Edition, Cambridge, Massachusetts, Orion Research, Inc., 1973. U. S. Department of Health, Education and Welfare, "The Industrial Environment, Its Evaluation and Control," HSM-99-71-45, Cincinnati: Public Health Service. Turner, H. C., "Methods for the Determination of Oil Mist," Annals of Occupational Hygiene, Vol. 18, Great Britain, 1975. Mindruk, R. F., Jr., "Determination of Organic Vapors in the Industrial Atmosphere, Bulletin No. 769, Supelco, Inc., Bellefonte, Pennsylvania, 1977. "Industrial Hygiene Sampling and Analytical Guide for Airborne Health Hazards," Ε. I. DuPont de Nemours & Co. (Inc.), 1978. RECEIVED August 14, 1979.


Occupational Health Chemistry - ACS Publications - American

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