Factors Influencing Personal Exposure to Nitrogen Dioxide in an Indian Metropolitan Region

This study was carried out in a mixed residential and industrial area of Mum bai. Nitrogen dioxide (NO2) concentrations were measured over 2-day periods both in winter (Feb. 1996) and summer (April 1996). Personal exposures as well as indoor and outdoor levels were monitored for 43 respondents. Personal exposures were found to vary substantially among the respondents, ranging from 10.2 to 87.5 ppb with a mean of 43.7 ± 16 ppb in winter and 23.6 ± 7.8 ppb in summer. Regression analysis of the data showed that there is a 37 and 47% correlation of personal exposure with indoor and outdoor concentration, respectively. ANOVA results showed that season of the year, house size and outdoor occupation significantly influenced the personal exposure to NO2 whereas it was not influenced by factors like type of fuel used and ambient air quality level. Personal exposure to NO2 was significantly greater in winter than in summer. Respondents staying in smaller houses and/or having out door occupation were exposed to higher NO2 levels.