Academic journal article Environmental Health Perspectives

Reducing Health Risks from Indoor Exposures in Rapidly Developing Urban China

Academic journal article Environmental Health Perspectives

Reducing Health Risks from Indoor Exposures in Rapidly Developing Urban China

Article excerpt

Rapid industrial and economic development in China over the past three decades has resulted in a large migration from rural areas to cities, urban growth, and modernization and a concomitant increase in urban air pollution. As shown in Figure 1, during the period from 1990 to 2010 the urban population more than doubled, net urban residential building area grew from 4 billion to 21 billion [m.sup.2], and the number of motor vehicles increased from 5 million to 78 million. The nature of indoor environments also changed as a consequence of using the different building materials, construction practices, and climate control that accompanied the replacement of low-rise dwellings with high-rise apartment buildings. Emblematic of changing building materials is the increased production of synthetic wood [from 15 million [m.sup.3] in 1999 to 154 million [m.sup.3] in 2010 (State Forestry Administration-People's Republic of China 2011)], and indicative of changing climate control is the increased presence of mechanical cooling in urban residences [from < 1 million air conditioners in 1990 to > 100 million in 2010 (National Bureau of Statistics-People's Republic of China 2011)]. As a result of these and other developments, China's cities have been experiencing rapid and dramatic changes in outdoor and indoor environments. These changes have affected hundreds of millions of people.

Here we discuss how urbanization and modernization in China have resulted in changes in indoor exposures to pollutants that originate both indoors and outdoors. We then examine ill health associated with these pollutant exposures and suggest policies that might be implemented to mitigate these adverse health effects.

Discussion

The changing nature of indoor exposure to indoor and outdoor pollutants. The inhabitants of China's cities spend most of their time indoors (Wang et al. 2008). Their indoor environments contain pollutants from outdoor sources (e.g., coal and oil combustion used in power plants, industry, and heating; motor vehicles; fugitive emissions; metallurgy; and biomass burning) as well as indoor sources (e.g., occupants, unvented combustion, building materials, furnishings, paint, floor and wall coverings, cleaning products, pesticides, appliances, and electronics). Pollutants emitted by indoor sources have changed dramatically over the past 30 years, reflecting the increased use of plastics, polymeric floor and wall coverings, synthetic wood products, and synthetic cleaning agents (Wang et al. 2010; Weschler 2009).

These changes have led to higher concentrations of various organic compounds in the indoor environments of China's cities [Bai et al. 2002; Edward et al. 2003; Guo and Kannan 2011; Hsu et al. 2012; Liu ZR et al. 2012; Wang et al. 2010; Wu et al. 2003; Zhang et al. 2009; see also Supplemental Material, pp. 2-3 and Table S1 (http://dx.doi. org/10.1289/ehp.1205983)]. The increased use of mechanical cooling (air conditioning) has decreased ventilation rates during warm periods and amplified exposures to pollutants from indoor sources (Meng et al. 2009).

Outdoor air in China tends to be more polluted in cities than in rural and semirural areas, reflecting emissions from power plants, industrial facilities, and motor vehicles. Urban levels of P[M.sub.10], P[M.sub.2.5] (particles with aerodynamic diameters of [less than or equal to] 10 or [less than or equal to] 2.5 um, respectively), ozone ([O.sub.3]), nitrogen oxides, and sulfur dioxide (S[O.sub.2]) are among the highest in the world (Kan et al. 2012; Zhang et al. 2012). In Beijing in 2011, the average annual level of P[M.sub.2.5] was roughly an order of magnitude higher than that in Boston, Massachusetts; Chicago, Illinois; or Washington, DC (Dominici and Mittleman 2012). These outdoor pollutants are transported indoors via ventilation and infiltration. Given the amount of time that people spend indoors, for many urban residents the major fraction of their exposure to "outdoor pollutants" occurs indoors (Chen C et al. …

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