We investigate wintertime indoor air quality and personal exposures to carbon monoxide (CO) in a rural village in Jilin province, where relatively homogeneous climatic and sociocultural factors facilitate investigation of household structural, fuel-related, and behavioral determinants of air pollution as well as relationships between different measures of air quality. Our time-resolved wintertime measurements of carbon monoxide and respirable particles (RSP) enable exploration of peak pollution periods in a village in Jilin Province, China, characterized by household use of both coal and biomass, as well as several "improved" (gas or electric) fuels. Our data indicate a 6-fold increase in peak 1 h PM (1.9 mg/m3) concentrations relative to 24 h mean PM (0.31 mg/m3). Peak 1 h CO concentrations (20.5 ppm) routinely approached and often (27%) exceeded the World Health Organization's 1 h guideline of 26 ppm, although the vast majority (95%) of kitchens were within China's residential indoor air quality guideline for CO on a 24 h basis. Choice of heating fuel and household smoking status were significant predictors of indoor air quality. Whether solid or "improved" (gas or electric) fuel was used for cooking had an even stronger effect, but in the opposite direction from expected, on both peak and daily average measures of air pollution. Peak pollution period concentrations of CO and PM were strongly correlated to daily concentrations of CO and RSP, respectively. Our results suggestthat due to the primary role of heating as a determinant of wintertime indoor air quality in northern Chinese villages, health-oriented interventions limited to provision of improved cooking fuel are insufficient. Our results illustrate that peak pollution periods may routinely exceed exposure regulations and evacuation limits, although this and previous studies document typical 24 h CO concentrations in rural Chinese kitchens to be within guidelines. Within a given village and for a given pollutant, daily pollutant concentrations may be strong predictors of peak pollution period concentrations.

Rural kitchens of solid-fuel burning households constitute the microenvironment responsible for the majority of human exposures to health-damaging air pollutants, particularly respirable particles and carbon monoxide. Portable nephelometers facilitate cheaper, more precise, time-resolved characterization of particles in rural homes than are attainable by gravitational methods alone. However, field performance of nephelometers must contend with aerosols that are highly variable in terms of chemical content, size, and relative humidity. Previous field validations of nephelometer performance in residential settings explore relatively low particle concentrations, with the vast majority of 24-h average gravitational PM 2.5 concentrations falling below 40 mg/m 3 . We investigate relationships between 24-h gravitational particle measurements and nephelometric data logged by the personal DataRAM (pDR) in highly polluted rural Chinese kitchens, where gravitationally determined 24-h average respirable particle concentrations were as high as 700 mg/m 3 . We find that where relative humidity remained below 95%, nephelometric response was strongly linear despite complex mixtures of aerosols and variable ambient conditions. Where 95% relative humidity was exceeded for even a brief duration, nephelometrically determined 24-h mean particle concentrations were nonsystematically distorted relative to gravitational data, and neither concurrent relative humidity measurements nor use of robust statistical measures of central tendency offered means of correction. This nonsystematic distortion is particularly problematic for rural exposure assessment studies, which emphasize upper quantiles of time-resolved particle measurements within 24-h samples. Precise, accurate interpretation of nephelometrically resolved short-term particle concentrations requires calibration based on short-term gravitational sampling.

No abstract

An open fire was assembled with firebricks to simulate the household fire pit used in rural China, and 15 different coals from this area were burned to measure the gaseous and particulate emissions. Particle size distribution was studied with a microorifice uniform-deposit impactor (MOUDI). Over 90% of the particulate mass was attributed to sub-micrometer particles. The carbon balance method was used to calculate the emission factors. Emission factors for four pollutants (particulate matter, CO2, total hydrocarbons, and NOx) were 2-4 times higherfor bituminous coals than for anthracites. In past inventories of carbonaceous emissions used for climate modeling, these two types of coal were not treated separately. The dramatic emission factor difference between the two types of coal warrants attention in the future development of emission inventories.