A Study on the Indoor-Outdoor NO2 Levels and Personal Exposures to NO2 with Analysis of Factors Affecting the NO2 Concentrations: Centering on Urban Homes and Housewives

Chun, Jin Ho; Lee, Chae Un; Kim, Joon Youn; Chung, Yo Han

Abstract

This study was conducted to establish the control program for preventing unfavorable health effects of nitrogen dioxide(NO2) exposure in homes by preparing the fundamental data for evaluation of relationships between NO2 levels and influencing factors through measurements of indoor-outdoor NO2 levels and personal NO2 exposures for housewives with questionnaire survey on 172 homes in Pusan area from April to June, 1987. NO2 measurements were made by using diffusion tube samplers(Palmes tube NO2 sampler) for one week at 4 sites in homes ; kitchen(KIT), bedroom(BED), living room(LIV), outdoor(OUT) and near the collar housewives(personal exposure livel, PNO). The details of questionnaire were number of household members(FAM), number of regular smokers(SMOKER), daily number of meals eaten(MEAL), type of housing units(HOUSE), location of house with distance from the heavy traffic roads as walking time(DIST), and of kitchen(KAREA), kind of cooking fuels(FUEL), cooking time of each meal(CTIME), usage of kitchen fan for cooking(FAN), type of heating facilities(HEAT) and so on of subject homes. The obtained results were as follows : 1) The mean NO2 level was significantly higher at indoors than outdoors(p<0.01) and the kitchen NO2 level was the highest with 33.7+/-13.6ppb(9.5-81.5ppb). The mean personal exposure level of NO2 for housewives was 20.6+/-8.8ppb(3.1-46.9ppb). 2) The mean indoor NO2 level was significantly higher in the group of household members above 5 than below 4(p<0.05), in detached dwellings than apartments(p<0.001), within 5 minutes of distance than over 5 minutes(p<0.001), in the group of unusing fan(p<0.001), in the group of longer cooking time(p<0.001), and it was in order of coal briquette, gas, electricity and oil by kind of cooking fuels(p<0.05). 3) Variables showing significant correlation(p<0.001) with indoor NO2 level were kitchen NO2 level(r=0.8677), cooking time(r=0.5921), outdoor NO2 exposure level(r=0.4615), usage of kitchen fan(r=0.3573) and location of house(r=-0.2988). 4) As a result of multiple regression analysis, the most significant influencing variable to the kitchen NO2 level was cooking time [KIT=-0.378+/-11.772(CRIME)+0.298(OUT)+3.102(FAN)], it was kitchen NO2 level to the indoor NO2 level [IND = 6.996+0.458 (KIT) + 0.230 (OUT) - 1.127 (KAREA)], and it was indoor NO2 level to the personal NO2 exposure level [PNO=15.562+0.729(IND)-4.542(DIST)-0.200(KIT)]. 5) It was recognized that artificial ventilation in the kitchen, suppression of unnecessary combustion and replacement of cooking fuel, as much as possible, were effective means for decreasing indoor NO2 levels in homes.