The recent analysis conducted by the Centre for Science and Environment (CSE) has highlighted an apparent increase in ozone levels in several cities across the nation, triggering concerns for public health. The research took into consideration data from the Central Pollution Control Board (CPCB) gathered from 22 cities in 15 states. Interestingly, while the levels of harmful ozone appear to be on the rise, the study observed a dip in particulate matter and nitrous oxide levels during the lockdown implemented to curb the Covid-19 spread.
Understanding Ozone Gas
Ozone is a complex gas with both beneficial and harmful effects, depending largely on its location in the atmosphere. The so-called ‘good’ ozone is found in the earth’s ozone layer where it serves as a protective shield against detrimental Ultraviolet (UV) radiation. However, ground-level ozone, which is highly reactive, can have adverse impacts on human health, posing significant risks for individuals with respiratory conditions and asthma. Even short-term exposure can prove dangerous.
Unlike other pollutants, ozone is not directly emitted by any source. Instead, it forms as a result of photochemical reactions between oxides of nitrogen (NOx), volatile organic compounds (VOCs), and gases in the air under the influence of sunlight and heat. It is an indicator of vehicular pollution, which contributes to higher concentration of NOx.
The Phenomenon of Summer Pollution
Interestingly, ozone pollution aligns closely with weather patterns and atmospheric conditions. The gas is primarily a “sunny weather problem” in India, with the formation of ground-level ozone directly linked to the presence of sunlight. Heat acts as a catalyst, facilitating photochemical reactions and leading to higher concentrations of ozone in the summer months.
Moreover, the intense heat waves are among the factors responsible for increased ozone levels. Typically, ozone levels spike when winter conditions subside and are most pronounced during daylight hours. At night, ozone levels tend to decrease, only to rise again during the afternoon when sunlight is available. Consequently, summer pollution is characterized by high winds, intermittent rains, thunderstorms, high temperature, and heat waves.
Particulate Pollution Amid Lockdown
While the levels of ozone have been raising concerns, there has been a significant drop in particulate pollution during the lockdown. In fact, average PM 2.5 levels during this period were found to be lower than the average for the same time span in 2019. However, as restrictions began to be relaxed and traffic returned to the roads, pollution started to increase once again.
The Way Forward
Given the apparent escalation in ozone levels, it is vital for the government to take proactive steps to mitigate primary pollutants that lead to ground ozone formation. These measures can include curbing private vehicle usage, promoting electric mobility, expanding public transport and pedestrian infrastructure, implementing citywide parking management, and strictly controlling industrial emissions. It is clear that addressing this issue effectively requires a comprehensive, multi-faceted approach.
