COVID‑19 LOCKDOWN SIGNIFICANTLY REDUCE URBAN AIR POLLUTION: A Study of Kolkata Metro City (India)

The deadly novel coronavirus (SARS CoV2) smashes the normal rhythm of global socio-economic life and livelihood by creating a disastrous pandemic disease (COVID-19). Almost all the countries impose a long-term lockdown to maintain social distancing as it is one only way to reduce the rapid man-to-man transmission of this virus. Consequently, this lockdown significantly impacts on reducing air pollution levels in the small town to megacities around the world due to the reduction of vehicle movements, industrial works, burning of biomass, and dust particles from the construction works.

Diesel vehicles are highly responsible for air pollution in Kolkata (Source: NK Realtors)

A recent study by a group of researchers guided by Dr. Biswajit Bera reveals the reducing air pollution level in Kolkata megacity in India. They try to examine the recent status of air quality and compare the result with pre-COVID-19 conditions. The research shows that significant air pollutants like CO, NO₂, and SO₂ are decreased drastically. On average about 17.5% reduction of Particulate matters (PM₁₀ and PM_2.5) are observed during the lockdown phase compared to previous years. In contrast, ozone gas slightly increased.

The variation of land surface temperature (LST) from March 25 to May 15 in 2019 and 2020 (Credit: Biswajit Bera et. al., 2020)

The earth's surface temperature is slight falls during lockdown because of controlled economic and industrial activities. Long-term lockdown due to the COVID-19 pandemic extremely affects the economic supply chain, socio-cultural aspects in life, education system, the mental health of the people, etc in most of the nations around the world. Therefore, the environment becomes capable to restore its balance through homeostatic systems thanks to the provisional shutdown of industrial, commercial, and transportation activities. Consequently, in Kolkata, the improvement of air quality and the declining trend of urban temperature bring some healthy environment to the city people.

The variation of aerosols optical depth (AOD) over Indian subcontinent from 2016 to 2020 and Spatio-temporal anomaly of AOD in 2020 compared with 2016–2019 (Credit: Biswajit Bera et. al., 2020)

A Massage towards People

This unwanted lockdown due to the COVID-19 pandemic suggests an important message to all the people, policymakers, and administrative authorities of the countries around the world for restoring the environmental quality as well as natural ecosystem stability. It seems that the world economy faces a massive disruption and millions of people going through a critical economic condition as they lost their work in different industrial and commercial sectors. Social life and human behavior suddenly change to a new dimension as people should have to maintain social distancing in public places or their workplaces. The entire education system in the world has changed to an online-based teaching-learning process. So people should have to understand the process of adaptation in critical unprecedented conditions.

On the other hand, this temporary lockdown helps the purification process of our environment along with air quality adjustment which has become undoubtedly the precious gift to human civilization. As we are well aware of the continuous damage of the environment with extreme pollutants in the air, water, soil everywhere and resultant global warming, sea-level rise, ice melting, etc. So, this unwanted situation brings some positive aspects towards humans and our only habitable earth. The researchers suggest that this deadly pandemic offers an enormous possibility to rejuvenate the environmental health all over the city where the urban modern livelihood, economic processes damages the environmental quality. At present, lockdown and resultant changing life system would be the best exercise for all the industrial countries to reduce all forms of environmental pollution as well as degradation. Simultaneously, policymakers should build sustainable indigenous models considering such researches for the cohabitation with the environment and that would be beneficial for environmental health especially for a populous city like Kolkata.