Wide fluctuations in concentrations of pollutants and lack of any clear trend during the much-discussed odd-even experiment suggests that no single action can substantially reduce air pollution levels in the capital, the Central Pollution Control Board (CPCB) has said in a report.
"With no clear trend and wide fluctuations observed in the concentrations, it is evident that meteorology and emissions from other polluting sources have been major factors impacting air quality of Delhi during the period," says the report that analyses air quality in Delhi before, during and after the odd-even experiment.
Data for days preceding the odd-even scheme, from December 25 to 31, shows that PM 10 and PM 2.5 ranged between 142-453 micrograms/ m3 and 52-298 micrograms/ m3 respectively. During the January 1-15 odd-even period, PM10 and PM2.5 values were 161-629 micrograms/m3 and 79-507 microgram/m3. And in post-odd even January 16-21, the value for PM2.5 were 76-342 microgram/m3.
The lower end of PM2.5 values before the odd-even scheme is less than during and after phases while the higher end were also less at 298 and 342 microgram/m3, indicating the role of weather conditions and other pollutants. The highest observed level for PM2.5 during the odd-even period was 507 microgram/m3.
The reduction of a certain number of cars on a daily basis would have reduced emissions but the difficulty in pinning down any change due to the odd-even scheme lies in the relatively smaller contribution of passenger cars and other sources. A recent IIT Kanpur study says one-third of Delhi's pollution is from outside the city while the weather also plays a crucial role .
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Times of India
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