An analysis done by the Centre for Science and Environment (CSE) of air pollution levels in 22 cities across India has revealed that ozone levels increased during the nationwide lockdown. CSE analysis reveals that while PM2.5 (particulate matter) and NO2 (nitrogen dioxide) levels fell and flattened in many cities, tropospheric ozone pollution increased and even breached standards in several cities. This study of CSE is based on data from 1 January to 31 May 2020. These figures have been collected from the Central Pollution Control Board. Even when PM2.5 and NO2 levels plummeted to the lowest in most cities during the lockdown and caught public attention, invisible ozone raised its ugly head on several days and in several cities.
According to the CSE report, global rules were adopted to measure pollution levels so that accurate analysis could be revealed. The report says if the maximum eight-hour average during 24 hours is considered then more than two-thirds of the lockdown days in Delhi-NCR cities and Ahmedabad had at least one station that exceeded the standard. At the same time, in Noida, Uttar Pradesh, ozone pollution was above the standard for 12 days and at one observation station, pollution was recorded above the standard for 42 days. Similarly, ozone pollution in Kolkata, Delhi and other cities exceeded the standard. However, Chennai and Mumbai did not register a single day of excess at the city-wide level, but at least one station in both exceeded the standard for several days.
The Central Pollution Control Board (CPCB) publishes the daily Air Quality Index (AQI) bulletin to inform about the severity of the pollution every day. With all pollutants down during lockdown, Ozone, even at a comparatively lower level, became the most prominent pollutant of the day in several cities and led the daily AQI. It may be noted that for AQI, the CPCB considers the fixed time slot of 8 PM to 4 PM which may not be the worst average of the day.
As per Anumita Roychowdhury, executive director-research and advocacy, CSE, “This pandemic has shown that big reduction is possible only if all regions clean up together and at a scale and speed across all critical sectors including vehicles, industry, power plants, waste, construction, use of solid fuels for cooking and episodic burning. There is a need for an agenda for a ‘blue sky and clear lungs’ for the post-pandemic period to sustain the gains. This action must also ensure the co-benefit of reducing both particulate and gaseous emissions, including ozone.”
What is the Centre for Science and Environment (CSE)?
Centre for Science and Environment (CSE) is a not-for-profit public interest research and advocacy organisation based in New Delhi, India. CSE uses knowledge-based activism to create awareness about problems and propose sustainable solutions. In 2018, CSE was awarded Indira Gandhi Prize for Peace, Disarmament and Development.
What is Ozone?
Ozone (O3) is a highly reactive gas composed of three oxygen atoms. It is an inorganic molecule with the chemical formula O3. It is a pale blue gas with a distinctively pungent smell. Ozone has two properties of interest to human health. First, it absorbs UV light, reducing human exposure to harmful UV radiation that causes skin cancer and cataracts. Second, when inhaled, it reacts chemically with many biological molecules in the respiratory tract, leading to several adverse health effects.
Effect of Ozone Pollution
On ozone inhalation, one may face many health problems including chest pain, cough and throat pain. People most at risk from breathing air containing ozone include people with asthma, children, older adults, and people who are active outdoors, especially outdoor workers.
