Exposures to nitrogen dioxide in EXPOLIS-Helsinki: microenvironment, behavioral and sociodemographic factors.

Personal exposures to nitrogen dioxide (NO(2)) were monitored for 176 randomly selected inhabitants (25-55 years old) of Helsinki Metropolitan area as a part of the EXPOLIS (Air Pollution Exposure Distributions Within Adult Urban Populations in Europe) study between October 1996 and December 1997. NO(2) measurements were 48-h averages collected by Palmes passive sampler tubes. Differences in personal exposures to NO(2) were analyzed between sub-populations stratified by microenvironment, behavioral, socioeconomic and demographic factors. Factors significantly associated with differences in exposures to NO(2) were home and work location, housing characteristics, traffic volume near home, season and keeping windows open at home. Exposure to environmental tobacco smoke (ETS) and use of gas stove were also associated with increased personal exposures, although only few participants had a gas stove in Helsinki, and other gas appliances are non-existent. Single adults had higher average exposures to NO(2) than married or cohabiting participants, suggesting differences in living conditions between these two groups. Increased education was associated with decreased exposures to NO(2) and employed men were more exposed than unemployed men. Increased exposures to NO(2) were not associated with age or occupational status in Helsinki. Thus, behavioral and sociodemographic factors may have significant impact on personal exposures to NO(2) and should be considered in addition to environmental determinants in any monitoring program.