Biomass energy, indoor air pollution and health
Auke Koopmans, formerly Chief Technical Advisor of the FAO Regional Wood Energy Development Programme in Asia, is an independent consultant in Chiangmai, Thailand.
Households that use biomass energy require efficient stoves to reduce smoke, particles and gases that are hazards to the health of women and children.
Biomass (wood, charcoal, agricultural residues, dung, etc.) is widely used as a source of energy in developing countries. Rough estimates indicate that worldwide one-third of the population or about 2 billion people depend on these sources of energy (UNDP/UNDESA/WEC, 2000). Biomass energy is used primarily to cook food, mainly using traditional or improved stoves (but also open fires). However, wood stoves may at the same time also be used as space heaters, as lamps, to repel insects, to preserve thatched roofs, to dry crops and fish, and so on. The simple wood stove is an integral part of the household, which is rarely true of modern stoves. This may be one of the reasons why it has been difficult to introduce better stoves or to change the cooking environment.
Improvements are needed, however, as evidence gathered over the past two decades shows that traditional multifunctional wood- or other biomass-burning stoves are not very efficient and that they often emit considerable amounts of smoke, soot, particulates and many kinds of harmful gases, which are potentially hazardous products of incomplete combustion (PICs). As a result, the cook – usually a woman – and small children in the home are exposed to high levels of indoor air pollution.
Results from studies carried out in developing countries indicate that particulate concentrations from traditional biomass-using stoves are often ten or more times higher than the standards set by the United States Environmental Protection Agency (Albalak et al., 1999). Exposure to these high levels of pollution has been consistently associated with acute respiratory infections, the largest single-category cause of morbidity and mortality worldwide (Smith et al., 2000). Evidence links exposure to biomass fuel combustion with chronic obstructive lung disease, tuberculosis, cataracts and adverse pregnancy outcomes (Albalak, Frisancho and Keeler, 1999; Perez-Padilla et al., 1996; Mishra, Retherford and Smith, 1999; Mohan et al., 1989; Mavlankar, Trivedi and Gray, 1991). The World Health Organization (WHO) has estimated that as many as 2 million people in developing countries, the majority under five years of age, die prematurely every year from exposure to the combustion products of household solid fuels (Albalak et al., 2001). The environmental burden of disease caused by indoor air pollution is second only to problems of water and sanitation (see Figure).
Besides being hazardous to human health, PICs are at the same time greenhouse gases. Thus reducing PIC levels will not only benefit health but also reduce greenhouse gases at the same time.
One of the easiest measures for reducing indoor air pollution, widely used in some Asian countries, is the installation of a chimney or a hood over the stove. This will reduce indoor air pollution but not air pollution in general, and it will not help in reducing greenhouse gases. Disadvantages include the cost, the potential for water leakage at the point where the chimney or hood vents through the roof, and the potential fire hazard if the roof is made from a combustible material such as leaves or thatch – therefore this system is not always used.
A switch to other less-polluting fuels such as commercial sources of energy (liquefied petroleum gas, kerosene, electricity, etc.) is another option. However, the cost of the stoves needed as well as of the energy itself is generally considered a barrier to the widespread adoption and use of these other energy sources by a large part of the population in developing countries.
A third option is to improve the stoves used. Initially this process was only technology driven, and improved stoves were not widely adopted (UNDP/UNDESA/WEC, 2000). Stoves need to be not only technologically efficient, but also easy to use, cheap and durable, if possible multifunctional, and usable with multiple fuels – in short, non-technical issues are equally, if not more, important.
Albalak, R., Bruce, N., McCracken, J., Smith, K.R. & Gallardo, T. 2001. Indoor respirable particulate matter concentrations from an open fire, improved cookstove, and LPG/open fire combination in a rural Guatemalan community. Environmental Science and Technology, 35: 2650-2655.
Albalak, R., Frisancho, A.R. & Keeler, G.J. 1999. Domestic biomass fuel combustion and chronic bronchitis in two rural Bolivian villages. Thorax, 54(11): 1104-1108.
Albalak, R., Keeler, G.J., Frisancho, A.R. & Haber, M.J. 1999. Assessment of PM10 concentrations from domestic biomass fuel combustion in two rural Bolivian Highland villages. Environmental Science and Technology, 33: 2505-2509.
Mavlankar, D.V., Trivedi, C.R. & Gray, R.H. 1991. Levels and risk factors for peri-natal mortality in Ahmedabad, India. Bulletin WHO, 69: 435-442.
Mishra, V.K., Retherford R.D. & Smith K.R. 1999. Biomass cooking fuels and prevalence of TB in India. International Journal of Infectious Diseases. 3(3): 119-129.
Mohan, M., Sperduto, R.D., Angra, S.K., Milton, R.C., Mathur, R.L., Underwood, B.A., Jaffrey, N., Pandya, C.B., Chhabra, V.K., Vajpayee, R.B., Kalra, V.K. & Sharma, Y.R. 1989. The India-U.S. case-control study group. India-U.S. case-control study of age related cataracts. Archives of Ophthalmology, 107: 670-676.
Perez-Padilla, J.R., Regalado, J., Vedal, S., Pare, P., Chapela, R. & Selman, M. 1996. Exposure to biomass smoke and chronic airway disease in Mexican women. American Journal of Respiratory and Critical Care Medicine, 154: 701-706.
Smith, K.R., Samet, J.M., Romieu, I. & Bruce, N. 2000. Indoor air pollution in developing countries and ALRI in children. Thorax, 6: 518-532.
UNDP/UNDESA/WEC. 2000. World Energy Assessment. New York, USA, United Nations Development Programme/United Nations Department of Economic and Social Affairs/World Energy Council.
World Bank. 1999. Environment matters – annual review. Washington, DC, USA.