Already dealing with the high particulate matters in the air, the national capital this summer has witnessed an alarming build-up of ozone, a Centre for Science and Environment (CSE) study said on Saturday.
According to the CSE findings, on several occasions and several locations, between February and May 2017, the ozone concentration was found to be very high — 3.4 times the normal standard.
"Early deaths due to ozone pollution are the highest in India. The new burden of disease study by Health Effect Institute has shown that early deaths due to ozone have jumped by 148 per cent in India," it said.
Additional analysis also shows heat waves and sunshine have increased the frequency of days with unhealthy levels of ozone.
Ozone, a more reactive form of oxygen, causes lung-related issues and heavy breathing. According to experts, its not directly emitted but is formed in a reaction between nitrogen oxides emitted from diesel vehicles and hydro-carbons in the presence of sunlight.
Its standards are based on hours -- the eight-hour standard concentration is 100 units (microgramme per cubic metre) and one-hour standard is 180 units.
"The share of days violating the eight-hour Cental Pollution Control Board (CPCB) standard of 100 microgram per cubic metre in February was 12 per cent -- this increased to 19 per cent in March, 52 per cent in April and finally a whopping 77 per cent in May," the CSE said, adding that the trend shows that the ozone pollution in the city was worsening progressively with the onset of summer.
"Delhi and NCR are in the grip of multi-pollutant crisis. Even before the health risk from particulate matter could be addressed, deadly ozone has raised its ugly head in Delhi and NCR.
"Without a time-bound implementation strategy and preventive action, this can deepen into serious public health crisis. This will spare neither the rich nor the poor," said Anumita Roychowdhury, Executive Director, Research and Advocacy and head of CSE's air pollution programme.
According to the experts, diesel vehicles are one of the major sources of the nitrogen oxides (NOx) and thus indirectly the ozone.
"Diesel vehicles produce five times higher the NOx than the petrol vehicles... The BS-6 standard fuel, which would be launched in India in 2020, would drop this emission by 80 per cent," said Vivek Chatopadhyay of the CSE.
He added that while normal masks could not save us from ozone, vegetation was also among the worse sufferers due to it.