Abstract

The current government strategies and public perception of air pollution in Bangladesh emphasize only on urban outdoor environment, but some of the highest concentrations of pollutants actually occur in rural indoor environment. The levels of air pollution exposed by the women and children below five years in the kitchens of many millions of village homes during cooking apparently exceed levels found in the worse polluted cities of the world. Excessive use of the low quality biomass fuels (i.e., wood, crop residues, animal dung, etc.) in inefficient traditional cooking stoves with no flue or chimney generates smokes, particulate, carbon monoxide, methane and hundreds of organic compounds including several carcinogens. Based on the studies conducted in other countries and available data from the literature, emission rates of various common air pollutants and green-house gases (GHG) representative of the typical cooking condition of rural Bangladesh are presented in this paper. For most compounds, it appears that solid biomass fuels such as wood burning produces markedly higher emissions than any other fossil fuel (i.e., kerosene, LPG, etc.). The biomass burning emissions vary with fuel type, stove design, combustion conditions, ventilation rates, and duration of cooking. It is possible to reduce emissions and exposure significantly by introducing a stove with higher level of efficiency. Recommendations are provided to formulate and implement a nationwide high efficiency cook stove dissemination program considering policy, economic, and social factors of Bangladesh.

Upon evaluating trends of national biomass energy consumption, total nationwide emissions of these pollutants are estimated. The total biomass derived emissions of the air pollutants and GHG's are then compared with those of other sectors. It appears from such comparison that in Bangladesh where rural life style dominates, indoor air pollution due to cooking is one of the most significant threats to human health and largest contributor of the global warming phenomenon. It is not, therefore, surprising to recommend shifting government and policy attention toward mitigation of wood stove pollution.

Among various hydrocarbons produced by the cook stoves, some hydrocarbons, e.g., benzene, 1,3-butadiene, styrene, and xylenes, are of special concern because of their carcinogenic properties. The lifetime risk of a typical woman in rural Bangladesh environment from exposures to these compounds emitted by cook stoves is tentatively estimated by using a simple exposure model and published cancer potencies. The results are very revealing. These estimates illustrate that doses and concentrations experienced by women and children in village homes burning biomass fuels are significantly high by any global standards. it is shown that village women who spend a significant period of a day in cooking activities receive a much larger total dose of pollution than residents of the dirtiest urban environments in the world, higher than any national public standards or World Health Organization's ambient air quality standards. Based on these calculations, it is estimated that use of biomass cook stove in rural Bangladesh generates substantially higher cancer risks (more than 80 times) than the maximum risk experienced by US population from all sources of airborne benzene and styrene. In fact, the woman cooks and children surrounding them inhale as much benzo(a)pyrene (BaP), a potent carcinogen, as some one who does smokes 20 packs of cigarettes each day. Under occupational safety and health regulations of today, relatively few workers in an industrial environment around the world are allowed to expose in such high levels.