Burning biomass fuels pollutes indoor air

By far the greatest threat of indoor pollution, however, still occurs in the developing countries, where some 3.5 billion people – mostly in rural areas, but also in many cities – continue to rely on traditional fuels for cooking and heating. (See Biomass Use, While Declining, Will Remain High.) Burning such fuels produces large amounts of smoke and other air pollutants in the confined space of the home a perfect recipe for high exposures. (Liquid and gaseous fuels such as kerosene and bottled gas, although not completely pollution-free, are many times less polluting than these unprocessed solid fuels.) In these circumstances, exposure to pollutants is often far higher indoors than outdoors. Indeed, the World Bank has designated indoor air pollution in developing countries as one of the four most critical global environmental problems (259).

As the table “Burning Biomass Fuels Pollutes Indoor Air” shows, concentrations of indoor pollutants in households burning dirty fuels are excessive. These estimates must be viewed with some caution, however, because monitoring in developing countries has been limited. Daily averages often exceed current WHO guidelines by factors of 10, 20, or even more. Peak levels during cooking may exceed these levels by a further factor of five or so. Indeed, these data suggest that many tens of millions of people in developing countries routinely encounter pollution levels reached during the infamous London killer fog of 1952, leading to a huge estimated toll in disease and premature death. One researcher estimates that as many as 2.8 million deaths per year result from breathing elevated levels of indoor smoke from dirty fuels (i.e., in excess of the WHO particulate standard). This finding translates to about 6 percent of all deaths each year (260). If this kind of effect is confirmed, indoor air pollution would be one of the largest single risk factors for ill health in the world.