IMPACT ON INDOOR AIR-QUALITY DURING BURNING OF PAKISTANI COAL BRIQUETTES

A comparison was made of airborne emissions from combustion of new types of Pakistani coal briquettes and traditional fuels. A mud-lined Angethi stove was operated under the standard nominal conditions of burning 200 g charges of fuel inside a 12-m3 shed with a forced rate of air exchange of 14 h-1. Coal was cold briquettes with lime, clay, and oxidant. Traditional fuels were wood, charcoal, and animal dung. Compared to raw coal, the amended coal gave fourfold reduced emission of respirable-size particles (RSP) while dramatically reducing overall SO2 release. Initial burning was restricted to the outer layers of the briquettes during which time reaction of SO2 with lime was incomplete and early emissions of SO2 were substantial. The measurements overall indicated that, with respect to CO, SO2, NO(x), and RSP, substitution of amended coal briquettes for traditional fuels will not worsen indoor air quality during domestic cooking. The traditional fuels and coal briquettes emit elevated peak amounts of CO (100-250 muL/L), SO2 (2-5 muL/L), and NO(x) (1-5 muL/L) in the early phase of volatiles burning with much reduced emissions in the later char-burning phase. Stove operators can substantially lower exposures by lighting the fuel outside and later moving the stove inside.