Exposure levels to fine particulate matter and carbon monoxide from solid biomass fuel use in Rural Western Kenya

Abstract

Globally, six million deaths annually are attributed to exposure to Indoor air Pollution (IAP) in developing countries due to pneumonia, chronic respiratory diseases and lung cancer, with the overall disease burden in Disability Adjusted Life Years (DALYs) exceeding the burden from outdoor air pollution by five-fold. In Kenya, respiratory infections account for 12% of annual deaths. This is due to overreliance on traditional biomass fuels which account for 90% of rural households and 70% of urban households as their primary cooking fuel. The objective of this study was to assess exposure levels to particulate matter (PM) and carbon monoxide (CO) from biomass fuel use in improved stoves and traditional stoves in Western Kenya region. The data was collected through continuous real-time monitoring of personal exposure levels for a period of 24 hours using CO monitors. Algorithms were used to estimate long term and short-term personal exposure of particulate matter from kitchen concentration levels. Data analysis was undertaken by first categorizing pollution data and exposure concentrations into three microenvironments then ANOVA done to test for their variations from WHO stipulated safe standards. At 95% CI, Maximum Daily Intake (MDI) of PM 2.5 was significantly higher using crop residues compared to wood fuel. Maximum daily intake using mud rocket stove was 889.889 μg/m 3 and 311.725 μg/m 3 using wood and crop residue fuels, respectively. Daily exposureof PM 2.5 using Chepkube stove was 442.354 μg/m 3 and 3518.6 μg/m 3 using firewood and crop residues fuels, respectively. Three-stone stove produced the highest daily exposure of 3646.5 μg/m 3 and 2768.5 μg/m 3 using crop residues and firewood fuels, respectively. Household indoor PM and kitchen concentrations associated with biomass fuel combustion in the study area exceeded WHO indoor safe limits of 25 μg/m 3 in the short term and 10 μg/m 3 in the long term and are in the hazardous range for human health. The extremely high kitchen PM 2.5 concentrations suggest that mud rocket stove and Cheprocket stoves cannot be an intervention for health effects of PM 2.5 which are of most interest in Household air pollution (HAP). Consequently, it is recommended that programs aiming to reduce exposure to CO and PM2.5 should focus on measures that result in larger reductions of PM2.5 emissions especially during burning and peak periods.