Monday, December 14, 2009

Monitoring What We Want to Manage & Mapping Urban Air Pollution in Delhi, India

If managing air pollution for better health is our primary goal, then we should monitor what we want to manage. Among the many pollutants, PM pollution is prevalent in most of the cities, and yet data available on ambient PM levels is limited for many reasons (read "hazy data").

The SIM-air working paper No.29 titled "Monitoring and Mapping Urban Air Pollution" presents a proposal (discussed earlier in September, 2009) to monitor PM pollution cheaply and effectively and a methodology to map the pollution over city for understanding the hot spots and studying exposure levels.

A pilot study was conducted in Delhi, India on October 3rd, 2009, covering ~160 km on road over 10 hours, recording PM10 and PM2.5 measurements at 1 min/1 sec intervals. During the experiment, average PM10 pollution over a 8 hour period = 206 micro-gm/m3; PM2.5 pollution over a 8 hour period = 163 micro-gm/m3; Black Carbon pollution over a 8 hour period = 36 micro-gm/m3. The collected data was interpolated over a map of Delhi for visualizing the extent of pollution exposure on a daily basis (shown below).

To the Northwest and West parts of the city, traffic movement was slow, especially along the major corridors, at the construction sites, which contributed to higher ambient pollution levels. The Northeast and East parts of the city also home for industrial areas. In the South, which is more residential, tends to experience on average 100 to 200 mg/m3, which is still above the national and WHO health guidelines. See animated monitoring route.

For the current observations, utilizing the average concentrations over Delhi, assuming at least 30% of the population (~5,000,000) is constantly exposed to these levels, and a dose-response function from premature mortality (0.000014 cases/mg/m3/percapita), a back-of-the-envelope calculation yields an annual mortality rate of ~10,900.

This at willingness-to-pay rate of ~US$50,000.00 (~25,00,000.00 Indian Rupees) translates to US$545 millions in health damages due to premature mortality annually.

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