Document ZJqBmpjY5DJbQMgkkJRkRMQjJ

. United States Environmental Protection - Agency Air Office of Air Quality Planning and Standards Research Triangle Park NC 27711 Assessment of EPA450/ 3-78431 June 1978 m- c Benz@ne ' J' ._,I' .- .. . 4 --- .I This reporr; is heirs circuiated 'by T e c k i c z l Literaturg Seccion. If you !inow cf sozeone e l s t who shsula see tbis repo,-t, oleose write that person's i n i t t d s cn a 2iece of :.=Fer., i n s e r t it in t k e 'moic F o c k t ar.8 ret-== t h e r e p o r t t o TIS. We bdli continue circulztisn. 33 NOT =i..-p ',his YPSGY~ directly 50 scEecce else. ! W iJ0T v r i t e anyone's i n i t i a l s on the cover of this r e m = . .- - - In t h e absence of adequate a t s o s p h e r i c monitoring d a t a , d i s p e r s i o n modeling w a s undertaken t o provide approximate estimates of benzene c o n c e n t r a t i o n s i n t h e v i c i n i t y of s p e c i f i c l o c a t i o n s . Chapters 111 through V d e s c r i b e dispersion modeling a n a l y s i s and r e s u l t s f o r t h r e e benzene p o i n t sources. In Chapter VIII, t h e Hanna-Gifford d i s p e r s i o n equation c was used to estimate average annual benzene c o n c e n c r a t i o n s in suburban -arcas ( s e e Table V I I I - 5 ) . If a background c o n c e n t r a t i o n of 0 . 5 ppb is i n c l u d e d , t h e estimated c o n c e n t r a t i o n s ranged from 0.73 t o 2 . 0 w b f o r - -suburban areas i n six large c i t i e s and a p p e a r t o be reasonably c l o s e t o t h e suburban values found i n Battelle's a m o s p h e r i c monitoring study ( s e e Table X-5). The hignes t benzene for a s h o r t period were ----__ __ _ - As shown in Table X-8, 8-hour average c o n c e n t r a t i o n s ranged f modelin3 r e to LG>nual averaqe benzene concentrations, however, are s k l a r t o / tnosa messured 5y S a t t e l l e along a major c o m u c i n g a r t e r i a l ( S i z e 2 on T a b l e X-5). The s e l e c t e d benzene exposure s e c t h g s f o r d e t e m i n i n g t o t a l e - q o s u r e a r e shown in Table T-9. These estimates r e p r e s e n t a combination of the b e s t nonitoring and modeling d a t a a v a i l a b l e t o d a t e and our b e s t judpenc. Althougn U n i t a t i o n s may be- involved i n using d i s p e r s i o n modeling data i n conjunction with monitoring d a t a , t h e methodology employed i n t h i s type of analysis does provide a more realistic e v a l u a t i o n of t o t a l exposure t o an i n d i v i d u a l . Several a d d i t i o n a l s t u d i e s a r e worth n o t i n g . A r e c e n t s t u d y by ?lesser A s s o c i a t e s , fnc., f o r t h e U.S. Department of T r a n s p o r t a t i o n (1977) analyzed the h e a l t h e f f e c t s of b i c y c l i n g in an urban environment by s t u d y i n g 10 male s u b j e c t s b i c y c l i n g o r d r i v i n g through t h e streets of Washington, D.C., under s y s t e m a t i c a l l y v a r i e d c o n d i t i o n s . No major a d v e r s e short- term e f f e c t s were noted, b u t t h e carboxyhemoglobin (COHb) l e v e l s measured f o r t h e m o t o r i s t c o n t r o l s were slightly h i g h e r than those for t h e b i c y c l i s t s . The a u t h o r s t h e o r i z e d (1) that t h e carbon monoxide (CO) encountered i n t r a f f i c slow-downs and i n t e r s e c t i o n d e l a y s may have 129 -.. ,. may, t o a l a r g e e x t e n t , explain why t h e sarrpling s t a t i o n s on t h a t side r e g i s t e r e d lower readings. As d i s c u s s e d i n Chapter VIII, most of t h e l i m i t e d atmospheric moni- t o r i n g d a t a have been c o l l e c t e d i n t h e v i c i n i t y of urban areas. Robinsoa et al. (1973) reported t h e r e s u l t s of s t u d i e s measuring hydrocarbon concentrations in th The measurements taken i n the continental Table X-7. They range from 0.3 t o 1.1 ppb, results appear t o be consistent with and benzene's low atmospheric r e a c t i v i t y . Radian Corporation (1978) monitored ambient benzene in Burnet, Texas, (a rural community) for Shell Oil Corporation. Three 24-hour samples were c o l l e c t e d on consecutive days under variable meteorologic c o n d i t i o n s . Complete q u a l i t y c o n t r o l information was unavailable-fo,=Qese data. Measured benzene c o n c e n t r a t i o n s range&fro/m---3 t o 4 ppb. The measurements / are n o t c o n s i s t e n t w i t h o t h e r s taken i k r e m o t e a r e a s . No explanation w a s o f f e r e d for t h e s e r e s u l t s . L B E N Z N E CONCE"I?IATIONSIX RE?IoTE AIR SAXEXES FROM THE CONTINENTAL UNITED STATES State California Idaho idaho Vermont Washing ton Location Point Reyes H e l l s Canyon Sample 1 Sample 2 zfoscow Mountain Ground Airborne C a m e l ' s Hump Brethway-Gunders on Ground Airborne Date 12/9/71 11/6/71 7/16/71 9/8/71 8/4/71 Benzene Concentration (pub) 0.3 0.8 0.8 0.9 0.8 1.1 0.4 0.5 Source: Washington S t a t e U n i v e r s i t y (1971) as c i t e d in Robinson e t al. (1973). 128 . .mm m4 c v) 2 0 Y II \ . .m-E4./r , U . .o \ m QJN am U Oh && U 4 0. 4. WO v(Y cy c'I -. 0. r,d IO 0.0. ma) a) . .(Yvr 04 -w rn :P ai a 0 I4 90 *m J 0 rJ u tn (I) a 0 &I a0 X f Io U P U +J r) cu Urn I C 0 r) u Ual 'c) 0 Lc a I=