Fuels such as wood and forest residuals are becoming important sources of energy; furthermore, wood and wood products are major components of building construction. In both cases environmental impact and health hazard posed by the burning of these materials must be evaluated. Most death and injuries on exposure to burning wood are due to inhalation of toxic gases, smoke, and heat gases, usually carbon monoxide. Any wood or wood products used in building construction must be chosen so as to release the minimum amount of toxic materials as slowly as possible when heated or burned, to allow people time to escape. The emissions from wood burning power plants certainly have local short term and global long term environmental impacts. For example, massive carbon dioxide production from wood burning is believed to affect the earth's energy balance and therefore global climates. This review does nol consider this aspect of wood burning, or other environmental hazards due to power plants utilizing wood, about which little seems to be known. The subject of this review is of the literature from 1971-1979 concerned with the toxicity of products of combustion and/or pyrolysis of wood, or wood products, untreated or treated with preservatives.