Unprocessed biomass fuels are still one of the most common fuels in the world. It is estimated that around 50 per cent of the world’s population, and more than 75 per cent of those living in developing countries rely on biomass fuels, such as wood, agricultural residues, and dung (Bruce et al, 2000; Reddy et al, 1997; WHO, 2002). Biomass combustion can release a considerable amount of various airborne pollutants, including particulates and carbon monoxide (CO). Especially when biomass stoves are placed indoors without a proper ventilation system, the indoor air pollutant levels are significantly higher than outdoor levels. There are several additional factors that make this circumstance far more hazardous:

there is a large population at risk;

stoves are used frequently;

stoves are used when people are present indoors; and

people, especially women and children, are close to the biomass burning.