Indoor PM and CO concentrations in rural Guizhou, China

Abstract

Household air pollution (HAP) from use of solid fuels varies greatly depending on stove technology, fuel, housing characteristics, season, and geographical area. Accurate information about indoor air pollution concentration as well as personal exposure is vital for more precise estimates of the health burden from HAP. We measured indoor fine particles ≤2.5μm in aerodynamic diameter (PM2.5) and carbon monoxide (CO) concentrations for 48h in 179 homes in winter and 122 homes in summer in rural Guizhou, China. Furthermore, we measured personal CO exposure among 1796 women. The highest median [25th–75th percentiles] PM2.5 kitchen concentrations were found in winter in biomass homes with an open fire (557 [303–882] μg/m3) or a stove without chimney (533 [210–770] μg/m3), while homes with a chimney stove had lower median kitchen concentrations (337 [212–1114] μg/m3 and 371 [192–1208] μg/m3 for biomass and coal, respectively). There was large seasonal variability with lower concentrations in summer for both PM2.5 and CO. Indoor CO concentrations were more correlated with type of fuel than stove technology, with higher median winter concentrations in kitchens using biomass (2.4 [0.9–4.6] ppm) than coal (0.7 [0.6–1.5] ppm). Personal CO exposure was relatively low, with median 1.3 [0.9–2.1] ppm. Stove and fuel type, ventilation, kitchen configuration, occupation, secondhand tobacco smoke, time spent outdoors, and ambient temperature were all associated with personal CO exposure. We found that CO could not be used as a suitable proxy for PM2.5 in this setting due to large heterogeneity in stove and fuel use within homes. We also found only a weak correlation between personal and indoor measurements, highlighting the importance of doing personal measurements in epidemiological research. Most households exceeded the PM10 Chinese indoor air pollution standard of 150μg/m3. Hence, continued efforts are needed to mitigate health damaging levels of HAP.