Daily Exposure to Air Pollutants in Indoor, Outdoor and In-vehicle Micro-environments: A Pilot Study in Delhi

The study measures exposure to air pollution in an urban setting in India. Integrated daily exposure to respirable suspended particulates (RSP) and carbon monoxide (CO) was assessed by personal and area sampling from six micro-environments including those for which prior data did not exist in India. This is also one of few studies that have measured the exposure of commuters on motor cycles, scooters, etc. A time budget survey was conducted to determine how much time people spend in these micro-environments. A sample of 1100 households (4311 individuals) was chosen randomly from 32 localities in Delhi for an activity patterns survey. Mean RSP levels during travelling ranged between 370-2860 μg·m -3 and CO levels from 8-19ppm. The weighted average of RSP daily exposure due to all micro-environments was 12.7mg·h·m -3 , with housewives and female workers being most exposed, largely because of cooking. The mean CO exposure was found to be 38ppm·h with workers the most exposed. We estimated that assuming people are exposed only to outdoor levels of RSP over 24h causes the true exposure to be underestimated by a factor of 1.7-2.7. Indoor RSP levels in homes, even in the absence of cooking, were found to be higher than expected. For all subgroups the daily average RSP concentrations were more than four times the ambient standards laid down by the Indian government. Only workers experienced daily CO average concentrations in excess of Indian standards (by a factor of 1.4).