Particulate matter exposure during domestic work in Nepal

Aims: To measure particulate matter (PM) exposure of people involved in domestic work (i.e. housework by a resident, not paid work) in urban and rural Nepal, with exposure to biomass smoke in the rural areas, and to examine the performance of photometric devices in collecting these data. This paper details the results of these measurements and derives calibration factors for two photometric devices compared to gravimetric measures. Methods: Between April 2006 and February 2007, respirable dust and PM2.5 levels were measured over a 24-h period in 490 households in a range of urban and rural settings in the Kathmandu valley of Nepal. Sampling was carried out by photometric and gravimetric methods with the co-located gravimetric data used to derive a calibration factor for the photometric devices. Results: The time-weighted average (TWA) (24 h) respirable dust levels measured by gravimetric sampler ranged from 13 to 2600 mu g m(-3) in the rural settings and 3 to 110 mu g m(-3) in the urban settings. The co-located photometric and gravimetric devices indicate that the SidePak Personal Aerosol Monitor device required a calibration factor of 0.48 and 0.51 for rural and urban data, respectively, whereas the DustTrak device required a factor of 0.31 and 0.35 for rural and urban settings to correct for the particle size and density of the biomass smoke. The photometric devices provide time history data on PM concentration levels and generally indicate two distinct peaks around a morning and early evening cooking time. Conclusions: Those involved in domestic work in rural Nepal are exposed to average respirable dust concentrations of similar to 1400 mu g m(-3). Converted to an 8-h TWA, this equates to more than the current UK limit for respirable dust (4000 mu g m(-3)). Homemakers, primarily women, spend a large proportion of their lives indoors in these high respirable dust concentrations and these exposures are likely to produce respiratory illness. Exposure can be controlled by the use of different fuel types and/or the use of flued stoves.