Indoor and Outdoor Air Pollution in the Himalayas

Air pollutant concentrations have been measured in residences in the Himalayas of Nepal where biomass fuels are used for cooking and heating. Levels of total suspended particles are in the range 3–42 mg/m³, with respirable suspended particles in the range 1–14 mg/m³ in the houses sampled. High concentrations of several trace elements have also been measured. Limited data for gaseous species show appreciable levels of carbon monoxide, carbon dioxide, methane, and several non-methane hydrocarbons. A questionnaire concerning energy use administered in each household suggests that high per capita use of biomass fuels is responsible for the excessive pollutant concentrations. Application of a one-compartment mass balance model to these houses shows only rough agreement between calculated and measured values, due to uncertainties in model input parameters as well as difficulties in estimating average pollutant concentrations throughout each house. High outdoor concentrations of potassium and methyl chloride, previously shown to be tracers of biomass combustion, indicate that the indoor biomass combustion also degrades the outdoor environment. Values of crustal enrichment factors for trace elements in the air and snow of the region suggest that the polluted air is generally confined to the populated villages, with more pristine air at higher elevations.