Shedding new light on wood smoke: a risk factor for respiratory health.

T he burning of wood is probably our oldest source for heating and cooking, and has been used by man for tens of thousands of years. Combustion of biomass, such as wood, animal dung and crop residues, is still used for cooking and heating by a large proportion of the global population, especially in less developed countries. In the industrialised world, and in countries with a cold winter climate, wood and other biomasses are widely used for heat production in residential wood log boilers, stoves and fireplaces. With the recognition of the limitations in amounts and durability of petroleum-based products, as well as an increasing concern regarding the issue of global warming, the interest in wood and other biomasses as alternative, sustainable and CO2neutral energy sources for fuel production and heating has emerged.