Exposure assessment for respirable particulates associated with household fuel use in rural districts of Andhra Pradesh, India

Abstract

Indoor air pollution associated with combustion of solid fuels seems to be a major contributor to the national burden of disease in India, but relatively few quantitative exposure assessment studies are available. This study quantified the daily average concentrations of respirable particulates (50% cut-off at 4 mm) in 412 rural homes selected through stratified random sampling from three districts of Andhra Pradesh, India and recorded time activity data from 1400 individuals to reconstruct 24-h average exposures. The mean 24-h average concentrations ranged from 73 to 732 mg/m 3 in gas-versus solid fuel-using households, respectively. Concentrations were significantly correlated with fuel type, kitchen type, and fuel quantity. The mean 24-h average exposures ranged from 80 to 573 mg/m 3 . Among solid fuel users, the mean 24-h average exposures were the highest for women cooks and were significantly different from men and children. Among women, exposures were the highest in the age group of 15-40 years (most likely to be involved in cooking or helping in cooking), while among men, exposures were highest in the age group of 65-80 years (most likely to be indoors). The data are being used to develop a model to predict quantitative categories of population exposure based on survey information on housing and fuel characteristics. This would facilitate the development of a regional exposure database and enable better estimation of health risks.

Field performance of a nephelometer in rural kitchens: effects of high humidity excursions and correlations to gravimetric analyses

“…As cooking episodes may be associated with high relative humidity excursions or dense plumes of condensed-phase species, our observations as well as previous works (see Table 1) call into question two assumptions implicit in previous use of the pDR to reconstruct human exposures to PM in rural Indian kitchens (Balakrishnan et al, 2004). First is the assumption that the relationship between gravimetric PM 3.5 and optically delineated PM is constant in time within a given household, or, more simply, that nephelometric response per unit particle mass is constant during cooking and noncooking episodes.…”

“…Published research results (reviewed below) based on nephelometric measurements in rural field settings are inconsistent with regard to data quality (i.e., nominal (factory-calibrated) readings vs data scaled to fit gravitational field samples, particle size fraction of gravimetric calibration) and treatment of temporal resolution (Brauer, 1995(Brauer, , 1996Ezzati et al, 2000a, b;Balakrishnan et al, 2004). Several studies have observed humidity-dependence of light scattering signals in ambient environments (e.g., Thomas and Gebhart, 1994;Richards et al, 1999;Day et al, 2000;Day and Malm, 2001).…”

“…Three previously published studies of indoor air quality in rural households use portable, passive-mode nephelometers to afford some level of temporal disaggregation not available from filter samples alone (Brauer et al, 1996;Ezzati et al, 2000a, b;Balakrishnan et al, 2004). Brauer et al infer from short-term measurements with the Radiance M903 nephelometer that peak particle concentrations in unvented biomassburning kitchens are significantly higher (Po0.05) than LPGburning and improved-stove counterparts, without quantifying the disparity.…”

“…Brauer et al infer from short-term measurements with the Radiance M903 nephelometer that peak particle concentrations in unvented biomassburning kitchens are significantly higher (Po0.05) than LPGburning and improved-stove counterparts, without quantifying the disparity. Using time-resolved particle data in kitchens, the other two studies demonstrate methodology for quantitatively characterizing exposures of cooks in India (Balakrishnan et al, 2004) and Kenya (Ezzati et al, 2000b Space heating, as well as some cooking, in Hechengli is primarily accomplished by the use of kangs. The traditional Han-style kang is an internal flue structure made from fired bricks.…”

“…Portable nephelometers have been welcomed as an advancement for assessment of human exposures to particles (Radojevic and Hassan, 1999;Ezzati et al, 2000a, b;Muraleedharan and Radojevic, 2000;Quintana et al, 2000Quintana et al, , 2001Williams et al, 2000;Rea et al, 2001;Lanki et al, 2002;Liu et al, 2003;Wallace et al, 2003Wallace et al, , 2006Balakrishnan et al, 2004;Wu et al, 2005a). However, most previously published environmental investigations of nephelometer performance relative to gravitational determinations depict controlled laboratory settings or relatively low (1-60 mg/m 3 ) particle concentrations (Richards et al, 1999;Howard-Reed et al, 2000;Quintana et al, 2000;Sioutas et al, 2000;Lanki et al, 2002;Liu et al, 2002;Wallace et al, 2003Wallace et al, , 2006Allen et al, 2004;Chakrabarti et al, 2004;Jenkins et al, 2004;Wu et al, 2005b).…”