The effect of enhanced stove design on ‘real life’ exposure to PM2.5 and CO in rural dwellings in Salambu, Nepal

About 3 billion people worldwide, and more than 90% in developing countries, are at risk of developing respiratory and cardiovascular diseases and cancer, due to exposure to household air pollution attributable to the combustion of solid biomass fuels. In Nepal, various types of fuel are used, such as wood, animal dung, and agricultural residues, as a primary source of energy for domestic cooking and heating.
This study examined real-time exposures to particulate matter (PM2.5) and carbon monoxide (CO) attributable to cooking in households in a rural environment in the village of Salambu, Nepal, for two daily cooking sessions (morning and evening). The real-time cooking exposure was monitored in houses containing one of two different cook-stove designs. The stoves were either a traditional cook stove (TCS) or an improved cook stove (ICS). The TCS is a simple single pot three stone open fire stove without a chimney, whereas the ICS is designed for improved efficiency and reduced emissions having two pots and a chimney. Kitchen PM2.5and CO concentrations were recorded at 10 seconds interval for actual cooking periods and one-minute intervals for periods of around 24 hours under real life conditions.
The real-time mean averages, μ, and standard deviations, σ, of PM2.5 and CO concentrations during cooking periods were μ=943.8ug/m3 (σ=426.5ug/m3) (13 households) and μ=13.5ppm (σ=5.2ppm) (13 households) respectively, in households using an TCS, and μ=334.6ug/m3 (σ=228.6ug/m3) (13 households) and μ=6.5ppm (σ=4.8ppm) (13 households) respectively in the households using an ICS. We conclude that the real-time concentrations of both PM2.5and CO are comparatively lower in the households using an ICS than the households using a TCS. However, average PM2.5 concentrations still exceed the WHO indoor air quality thresholds for PM2.5 and national air quality guidelines. Furthermore, average 24-hour kitchen PM2.5 and CO concentrations also exceed the WHO indoor air quality thresholds. Therefore, a significant proportion of the local population of this region remain likely to be at risk of developing diseases related to increased levels of air pollutants irrespective of their ownership of an ICS, although use of the ICS resulted in lower overall exposures and hence the absolute risk may be lower for those using an ICS. Additional measures to reduce exposures are required.