Particulate Matter fractions and kitchen characteristics in Sri Lankan households using solid fuel and LPG

Introduction: Use of solid fuel for cooking is a major source of household air pollution in developing countries. Of the many pollutants emitted during solid fuel combustion, Particulate Matter (PM)is considered to be one of the most hazardous pollutants. We monitored PM fractions emitted during solid fuel and Liquefied Petroleum Gas(LPG) combustion in kitchens of Sri Lankan households. Methods: Households of children in a longitudinal study in Ragama, Sri Lanka was the study population. At the age of 36 months of children, a sample of households were visited and different aerodynamic diameters of PM (PM1, PM2.5, PM10) were monitored during the main cooking session for 3 hours. Basic characteristics of kitchen (e.g., availability of chimney, functionality of chimney, etc.) were assessed by a questionnaire. Cooking energy, other sources of household air pollution, size of open spaces in the kitchen (e.g., windows), etc. were assessed at the time of PM monitoring. Results: Questionnaire was administered for mothers in 426 households. Out of them, 245 (57.5%)and 116 (27.2%) households used LPG and wood as the primary cooking fuel respectively. During the cooking period, PM2.5 concentrations of households uses only wood fuel and cook inside the main housing building were 344.1 micro grams per cubic meter(Inter Quartile Range(IQR) = 173.2-878.0), 88.7 micro grams per cubic meter (54.8 to 179.2 ), 91.7 micro grams per cubic meter (56.0 to 184.9) and 115.1 micro grams per cubic meter(83.4 to 247.9) in kitchen, sleeping room, living room and immediate outdoor respectively. Immediate outdoor PM2.5 concentrations in wood burning households was higher among households not having chimney (n = 8)compare to those having a chimney ( n = 8) (245.9 micro grams per cubic meter (IQR = 72.5 to 641.7)) VS. (105.7 micro grams per cubic meter(83.4 to 195.8)). Fuel type and stove type, availability of a chimney and their functional status, ratio between open space and total space of kitchen, PM2.5 concentration at the non-cooking time (i.e., baseline PM2.5concentration) were the determinants of PM2.5 in wood using kitchens during cooking period. Conclusions: PM concentrations were higher in kitchen and other microenvironments of the households use wood for cooking as compared to LPG use for cooking. Immediate outdoor PM concentration was higher than the sleeping and living room PM concentrations. Several factors determine the PM2.5 concentrations during the cooking including the fuel type.