January 27, 2016 12:53:26 am
Air quality levels dipped from early morning on Republic Day, with particulate matter levels shooting up across air quality monitoring stations. At least four AQI stations recorded severe levels of air pollution, with particulate matter (PM) 10 and 2.5 being the prominent pollutants.
Mandir Marg, R K Puram, Anand Vihar, Punjabi Bagh all recorded PM 2.5 levels between 400 and 500 micrograms per cubic metre (\µg/m³).
Real time readings of Delhi Pollution Control Committee (DPCC) stations showed PM 10 levels peaked between 700 and 800 µg/m³ across stations on Tuesday morning. Levels of PM 2.5 ranged between 400 and 500 µg/m³.
The levels however came down in the evening, to between 300 and 600 µg/m³ for PM 10 and 200-450 µg/m³ for PM 2.5 by around 7 pm, for the six stations under DPCC.
According to scientists, this marked a relatively poor Republic Day compared to last year, when rains triggered by westerly disturbances helped dispose of particulates. In the last week, the CPCB stations recorded severe to very poor air quality, sources said. In the last three days in particular, PM 2.5 levels spiked.
“During the odd-even scheme, even though the weather was similar to this week, the peaks in PM 2.5 levels were arrested. Now the peak values have gone up, even though the 24-hour average levels may still be in the same range for vehicular pollutants,” a scientist in DPCC explained.
Last week, the DPCC stations also recorded a rise in gaseous pollutants like Nitrogen dioxide and carbon monoxide, that are associated with vehicles.
“We could see from our analysis of data from roadsides in particular, these gaseous pollutants had come down during the implementation of the odd-even scheme. But these values have also spiked in the last three days,” the scientist added.
Many scientists however cautioned that there were wide variations in air quality during the January 1 to 15. CPCB, in its analysis report, said the odd-even scheme recorded “no clear trend or wide fluctuations” in the concentrations, attributing these observations, to emissions from other sources, despite of the control in vehicular pollutants during the scheme.
“It is evident that emissions from other polluting sources have been major factors impacting air quality of Delhi during the period. Overall, it can be stated that while some reduction in air pollution is likely to happen due to odd-even scheme, a single factor or action cannot substantially reduce air pollution in Delhi. A comprehensive set of actions following an integrated approach is required to make substantial improvement in air quality, “the CPCB report on the analysis of air pollutants associated with vehicles during the odd even scheme, states.
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