Indoor air pollution affects both urban and rural populations. Nor is it simply a problem indoors: numerous studies have shown that intense indoor coal burning can affect ambient air quality as well. For instance, rural neighborhoods are generally unaffected by urban sources of air pollutants but can be extremely polluted from the burning of coal indoors. Air Quality May be Worse Indoors shows the extremely high levels of particulates in both rural and urban indoor environments . Indoor air pollution causes as many health problems as smoking, with the effects concentrated among women and children .
Although the proportion of China’s households that burn polluting biomass fuels indoors for cooking and heating remains significant, it has been declining with the proliferation of alternative energy sources. Largely as a result of government investments, about one third of urban Chinese now have access to gas for cooking, and coal-burning households are increasingly turning to the use of cleaner, more efficient briquettes .
Perhaps the most compelling example of the health impact from indoor air pollution is the extremely high lung cancer rates among nonsmoking women in rural Xuan Wei County. Studies conducted by the United States Environmental Protection Agency (U.S. EPA) report that in the three communes with the highest mortality rates, the age-adjusted lung cancer mortality rate between 1973 and 1979 was 125.6 per 100,000 women, compared with average rates of 3.2 and 6.3 for Chinese and U.S. women, respectively, for the same time. Because surveys showed that virtually no women (in the county) smoked tobacco products, other sources of potent exposure must have contributed to these troubling rates. Analyses of indoor air and blood samples from the women indicate that fuel burning inside the home was largely responsible for the lung cancers. The U.S. EPA studies found a strong association between the existence of lung cancer in females and the duration of time spent cooking food indoors. The levels of carcinogenic compounds present in smoky coal (a local type of coal that smokes copiously) were found to be much higher in the women who used smoky coal for cooking  .
|Air Quality May be Worse Indoors|
|Indoor Air Particulate Air Pollution from Coal Burning in China (Sample Studies)
|PLACE||URBAN/RURAL||PARTICULATES (micrograms per cubic meter)|
Source: World Health Organization (WHO), Health and Environment in Sustainable Development: Five Years after the Earth Summit (WHO, Geneva, 1997), p. 86.
Note: a. Particles less than 10 micrometers in size.
39. Ibid., pp. 83<196>86.
40. Op. cit. 12, p. 19.
41. Op. cit. 12, p. 19.
42. Robert S. Chapman et al., “Assessing Indoor Air Pollution Exposure and Lung Cancer Risk in Xuan Wei, China,” Journal of the American College of Toxicology, Vol. 8, No. 5 (1989), pp. 941<196>948.
43. Judy L. Mumford et al., “DNA Adducts As Biomarkers for Assessing Exposure to Polycyclic Aromatic Hydrocarbons in Tissues from Xuan Wei Women with High Exposure to Coal Combustion Emissions and High Lung Cancer Mortality,” Environmental Health Perspectives, Vol. 99 (1993), pp. 83<196>87.