Combustion-generated contaminants - Indoor Environmental Quality - page 68

Figure 3.1 Polycyclic aromatic hydrocarbon concentrations associated with different

wood-burning heating appliances. (From Knight, C.V., Humpreys, M.P., and Pennex,
J.C., Proc. Indoor Air for Health and Energy Conservation , ASHRAE, Atlanta, 1986. With

permission.)

carcinogenic potential. PAH concentrations associated with a variety of
wood heater types, as well as outdoor concentrations, are indicated in Figure
3.1 . Lowest indoor PAH concentrations and potential human exposures were
associated with airtight wood stoves, particularly those equipped with cat-
alytic systems. Catalytic systems are commonly used to meet the wood
appliance NSPS.

II. Unvented combustion systems

A. Cooking stoves in developing countries

A majority of the world's households depend on biomass fuels, such as
wood, animal dung, and crop residues, for their cooking and space heating
needs, with wood being the principal fuel. Most biomass fuel use occurs in
rural areas of developing countries (particularly the densely populated
countries of Southeast Asia), although significant biomass fuel use also
occurs in poor urban areas. Unprocessed biomass fuels are the primary
cooking fuel in 75% of households in India, 90% of which use wood or dung.
Biomass fuels are at the high end of the fuel ladder relative to pollutant
emissions; not surprisingly they are at the low end of the ladder in terms
of combustion efficiency and energy content.
In addition to unprocessed biomass, other fuel types used for cooking
in developing countries include charcoal, kerosene, and coal. Unvented
coal-burning cooking fires are increasingly being used in China where pop-