Personal exposure to PM2.5, black smoke and NO2 in Copenhagen: relationship to bedroom and outdoor concentrations covering seasonal variation

Abstract

Epidemiological studies have found negative associations between human health and particulate matter in urban air. In most studies outdoor monitoring of urban background has been used to assess exposure. In a field study, personal exposure as well as bedroom, front door and background concentrations of PM 2.5 , black smoke (BS), and nitrogen dioxide (NO 2 ) were measured during 2-day periods in 30 subjects (20-33 years old) living and studying in central parts of Copenhagen. The measurements were repeated in the four seasons. Information on indoor exposure sources such as environmental tobacco smoke (ETS) and burning of candles was collected by questionnaires. The personal exposure, the bedroom concentration and the front door concentration was set as outcome variable in separate models and analysed by mixed effect model regression methodology, regarding subject levels as a random factor. Seasons were defined as a dichotomised grouping of outdoor temperature (above and below 81C). For NO 2 there was a significant association between personal exposure and both the bedroom, the front door and the background concentrations, whereas for PM 2.5 and BS only the bedroom and the front door concentrations, and not the background concentration, were significantly associated to the personal exposure. The bedroom concentration was the strongest predictor of all three pollution measurements. The association between the bedroom and front door concentrations was significant for all three measurements, and the association between the front door and the background concentrations was significant for PM 2.5 and NO 2 , but not for BS, indicating greater spatial variation for BS than for PM 2.5 and NO 2 . For NO 2 , the relationship between the personal exposure and the front door concentration was dependent upon the ''season'', with a stronger association in the warm season compared with the cold season, and for PM 2.5 and BS the same tendency was seen. Time exposed to burning of candles was a significant predictor of personal PM 2.5 , BS and NO 2 exposure, and time exposed to ETS only associated with personal PM 2.5 exposure. These findings imply that the personal exposure to PM 2.5 , BS and NO 2 depends on many factors besides the outdoor levels, and that information on, for example, time of season or outdoor temperature and residence exposure, could improve the accuracy of the personal exposure estimation. Keywords: urban air, particulate matter, PM 2.5 , black smoke, nitrogen dioxide, personal exposure, seasonal variation. Journal of Exposure Analysis and Environmental Epidemiology IntroductionNumerous studies have shown that exposure to high outdoor particle levels causes increased morbidity and mortality of respiratory diseases and cardiovascular diseases (Brunekreef and Holgate, 2002;Pope et al., 2002). Exposure to particles has been assessed by outdoor monitoring of urban background levels in most of these studies. It has been shown that people spend most of their time indoor and that indoors sources to air pollutants are n...

Exposure to fine particles (PM2.5 and PM1) and black smoke in the general population: personal, indoor, and outdoor levels

“…They were lower than levels found in central and southern Europe, and comparable to those found in the EXPOLIS study in Helsinki (Koistinen et al, 2001) or in Copenhagen (Sorensen et al, 2005). The levels of BS must likewise be considered low, being slightly lower than the results from Helsinki and Copenhagen and well below levels in cities such as Athens and Prague (Go¨tschi et al, 2002;Ha¨nninen et al, 2004).…”

“…Personal exposure exceeding indoor and outdoor concentrations has also been found in other studies investigating exposure to fine particles (Pellizzari et al, 1999;Koistinen et al, 2001;Lai et al, 2004;Sorensen et al, 2005;Meng et al, 2005). Our study included only three smokers, which could be one reason for the relatively small difference between personal exposure and indoor or outdoor levels.…”

“…Therefore, it is important to assess the relationship between personal exposure and ambient levels. Some recent studies have shown that urban ambient measurements do not always reflect personal exposure (Oglesby et al, 2000;Kousa et al, 2002;Sorensen et al, 2005).…”

“…The particles we inhale may come from industry, energy production, traffic, resuspension of dust, sea salt, a variety of indoor sources, and many other sources. Measurements of personal exposure to PM 2.5 have been conducted in several studies in recent years (the EXPOLIS study: Koistinen et al, 1999Koistinen et al, , 2001Oglesby et al, 2000;Kousa et al, 2002; the ULTRA study : Janssen et al, 2000; and other studies: Pellizzari et al, 1999;Kinney et al, 2002;Lai et al, 2004;Sorensen et al, 2005;Meng et al, 2005). Combustion-derived particles are largely found in the fine particle fraction or in the even smaller, submicron fractions.…”

“…Therefore, it is important to assess the relationship between personal exposure and ambient levels. Some recent studies have shown that urban ambient measurements do not always reflect personal exposure (Oglesby et al, 2000;Kousa et al, 2002;Sorensen et al, 2005).The aim of this study was to measure personal exposure to fine particles (both PM 2.5 and PM 1 ) and BS among the general adult population in Gothenburg and to examine the relationship between personal, indoor, and residential outdoor particle levels as well as urban background concentrations. The study design also allowed investigation of the within-(i.e.…”