Tuesday, May 10, 2011

Measured Exposure to Air Pollution in Delhi, India


On similar lines,

if managing the 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 the data available on the 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, the average PM10 pollution over the 8 hour period = 206 micro-gm/m3; PM2.5 pollution over the 8 hour period = 163 micro-gm/m3; Black Carbon pollution over the 8 hour period = 36 micro-gm/m3. The collected data was interpolated over the Delhi map to visualize the extent of exposure to pollution on delhi roads on a daily basis (shown below).

In the Northwest and West sections, traffic movement was slow, especially along the major corridors, along with construction activities, which contributed to higher ambient pollution levels. The Northwest and East sections also home for industrial areas. The South Delhi , which is more residential, tends to experience on average 100 to 200 mg/m3, which is well above the national standards 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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