Outdoor/Indoor/Personal Ozone Exposure in Nashville,Tennessee

摘要

An outdoor/indoor/personal ozone(O3)exposure study was conducted in Nashville,Tennessee,during the summer of 1994 using Harvard passive samplers to estimate weekly O3 exposures for a group of 10 to 12-year-old elementary school children.Thirty-six children from two Nashville communities participated in the study and 99 children provided additional time-activity information.Based on the continuous community monitors,weekly average outdoor O3 concentrations in the urban community ranged from 12 to 26 parts-per-billion(ppb)with a 20 ppb average and from 23 to 42 ppb with a 33 ppb average in the suburban community.Passive weekly average outdoor O3 concentrations ranged from 17 to 28 ppb;weekly average indoor concentrations ranged from 0.9 to 3.2 ppb(3 to 15 percent of outdoor levels)and weekly average personal exposures ranged from 1.3 to 6.4 ppb(7 to 31 percent of outdoor levels).Air conditioned homes exhibited negligible indoor O3 concentrations(64% of all indoor samples were below the minimum detection limit)whereas the few homes(5 of 36)identified as"frequently"opening windows experienced much higher indoor O3 levels(≈half of outdoor concentrations).Community O3 monitors overestimated personal exposure by a factor of seven and overestimated indoor exposure by an order of magnitude.The children did well in following directions concerning O3 exposure assessment and in keeping time-activity diaries.Clearly,those children spending more time outdoors were subjected to higher O3 exposures than their more home-bound classmates.While weekly ambient O3 concentration estimates from the urban community monitor agreed well with the outdoor passive sampler results,the suburban community monitor yielded consistently higher concentrations than the outdoor passive samplers.The suburban continuous community monitor encountered maximum 1-and 8-hour ambient concentrations exceeding the level of the 1-hour O3 National Ambient Air Quality Standard(NAAQS)once and the level of the 8-hour O3 NAAQS on four occasions.