“Pune and Mumbai are witnessing rising ozone levels much more than the safe limits,” stated the Central Pollution Control Board (CPCB) data. The same data has now been forwarded to the National Green Tribunal (NGT) on September 25 with respect to an ongoing case of the Centre for Science and Environment (CSE), which warned of rising ozone in Indian cities.
Though Delhi remains at the top for the ozone pollution levels but the CPCB’s new finding highlighting Pune and Mumbai rising up in the list is alarming.
As reported by Hindustan Times (HT), head of the Metropolitan Air Quality and Weather Forecasting Services (MAQWS) at Indian Institute of Technology and Management (IITM), Sachin Ghude, said, “On certain days, the ozone levels do exceed, mainly due to chemical reactions, and there is an urgent need for policies to control this overshoot.”
After analysing ozone levels from Kolkata, Hyderabad, Delhi, Bengaluru, Ahmedabad, Lucknow, Jaipur, Chennai, Mumbai and Pune, the CPCB concluded that Pune and Mumbai were found to be breaching the National Ambient Air Quality Standards (NAAQS) related to safe ozone limits.
Six out of twelve monitoring stations in the Pune Metropolitan Region were found to be violating the norms, while 22 out of 45 monitoring stations in the Mumbai Metropolitan Region were found to have eight-hourly exceedances.
In addition to this, violations were also reported during the night hours, along with some short-term spikes.
The ground-level ozone is formed due to complex non-linear photochemical reactions between two air pollutants: volatile organic compounds (VOCs) and nitrogen oxides (NOx), where sunlight and heat act as a catalyst, which aggravate ozone concentrations.
Also, methane (CH4) and Carbon Monoxide (CO) emissions through farm-related activities and residential sources add to the ozone pollution. And CPCB attributes the rise in ozone levels to industrial activities, power plants, and the logistics sector, which add to the NOx concentration.
Though there are also natural sources, such as soil, wildfire-induced Carbon Monoxide (CO), biogenic emissions of Volatile Organic Compounds (VOCs), and methane present in the biosphere.
“Nitrogen Oxides (NOx) play a major role in the rise of ozone levels in the atmosphere, particularly at high temperatures and in the presence of traffic congestion. Though the current level is not alarmingly high, it does have health implications. If not addressed timely, the levels are likely to rise further in the future,” Ghude explained to HT.
