Levels of ozone, a gaseous pollutant, have shown a spike in the last three days after dipping immediately once the second round of odd-even scheme came to an end on April 30, according to data collated by various monitoring agencies.
The Central Pollution Control Board’s (CPCB’s) air quality bulletins — from various monitoring stations — show that on both May 5 and May 7, ozone was one of the two dominant pollutants in the capital.
On Saturday, with an Air Quality Index (AQI) of 261 in the “poor” range, ozone and Particulate Matter (PM) 2.5 were recorded as the dominant pollutants in the capital, according to CPCB’s air quality bulletin. On May 5, with an AQI of 241, again in the “poor” range, ozone and PM 2.5 were found to be the dominant pollutants.
This is the first time ozone levels have gone up after the second phase of odd-even scheme came to an end.
Scientists say the spike in ozone could be attributed to the rise in temperature and rising levels of other pollutants, including particulate pollutants like PM 2.5.
“Ozone levels dipped in the 2-3 days after April 30 due to improved weather conditions, including a dip in temperatures and higher wind speeds. In the last few days, not only have gaseous pollutants like ozone spiked, but PM 2.5 and PM 10 levels have also increased,” said a CPCB scientist.
He added that the role of odd-even — in the dip in ozone levels immediately after the scheme — needed to be studied. “Compared to trends last year, temperatures and wind speeds seem to be playing a role here,” said the scientist.