Ozone levels rising in Pune & Mumbai, CPCB tells NGT
While Delhi remains the national hotspot for ozone pollution, the CPCB’s latest data highlights that Mumbai and Pune too are now firmly in the danger zone, necessitating immediate action from policymakers and civic authorities.
According to new data from the Central Pollution Control Board (CPCB), Maharashtra’s two major cities, Pune and Mumbai, are emerging as hotspots for ozone pollution with ozone levels frequently exceeding safe limits. The findings were submitted to the National Green Tribunal (NGT) on September 25 in response to a case based on a Centre for Science and Environment (CSE) report warning of rising ozone levels across Indian cities. While Delhi remains the national hotspot for ozone pollution, the CPCB’s latest data highlights that Mumbai and Pune too are now firmly in the danger zone, necessitating immediate action from policymakers and civic authorities.
Sachin Ghude, head of the Metropolitan Air Quality and Weather Forecasting Services (MAQWS) at Indian Institute of Technology and Management (IITM), said, “The ozone levels do exceed on certain days, mainly due to chemical reactions and there is an urgent need for policies to control this exceedance.”
The CPCB analysed data from 178 monitoring stations across 10 metropolitan regions including Delhi, Bengaluru, Kolkata, Hyderabad, Lucknow, Jaipur, Chennai, Ahmedabad, Pune and Mumbai. Both Pune and Mumbai were found to register significant violations of the National Ambient Air Quality Standards (NAAQS) for ozone. In the Pune Metropolitan Region (PMR), six out of 12 monitoring stations reported exceedances whereas in the Mumbai Metropolitan Region (MMR), 22 out of 45 monitoring stations reported eight-hourly exceedances. Short-term spikes in ozone levels were also noted. Nighttime breaches, which are relatively rare, were observed in both cities with one station each in Pune and Mumbai recording ozone levels over and above prescribed limits even after sunset. While Delhi recorded the highest number of violations nationwide, the CPCB’s analysis clearly placed Pune and Mumbai among the country’s most affected urban centres.
The CPCB report explained that tropospheric or ground-level ozone is formed primarily from complex non-linear photochemical reactions between two major classes of air pollutants: volatile organic compounds (VOCs) and nitrogen oxides (NOx). Besides, Carbon Monoxide (CO) and methane (CH4) emitted by residential and agricultural sources also play a role in ozone formation. These reactions typically depend on the presence of heat and sunlight, resulting in higher ambient ozone concentrations.
{{/usCountry}}The CPCB report explained that tropospheric or ground-level ozone is formed primarily from complex non-linear photochemical reactions between two major classes of air pollutants: volatile organic compounds (VOCs) and nitrogen oxides (NOx). Besides, Carbon Monoxide (CO) and methane (CH4) emitted by residential and agricultural sources also play a role in ozone formation. These reactions typically depend on the presence of heat and sunlight, resulting in higher ambient ozone concentrations.
{{/usCountry}}According to the CPCB, the elevated levels of ozone may be attributed to emissions from the transport sector, power plants and industrial activities, which collectively contribute to the overall NOx emission load. Additionally, ozone precursors may also originate from natural sources, including biogenic emissions of VOCs, soil-based emissions of NOx, wildfire-induced emissions of carbon monoxide (CO), and methane emissions from the biosphere.
{{/usCountry}}According to the CPCB, the elevated levels of ozone may be attributed to emissions from the transport sector, power plants and industrial activities, which collectively contribute to the overall NOx emission load. Additionally, ozone precursors may also originate from natural sources, including biogenic emissions of VOCs, soil-based emissions of NOx, wildfire-induced emissions of carbon monoxide (CO), and methane emissions from the biosphere.
{{/usCountry}}Ghude explained that NOx plays a major role in the rise of ozone levels in atmosphere, particularly at high temperatures and in the presence of traffic congestion. “Although the current exceedance is not alarmingly high, it does have health implications. If not addressed, the levels are likely to rise further in the future,” he said.
