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The Effects Of Corona Virus Lockdowns On Atmospheric Pollutants

The Effects of Corona Virus Lockdowns on Atmospheric Pollutants

Environmental pollution which is a growing concern globally is posing challenges to both developed and developing nations. However, global lockdowns due to the corona virus (COVID-19) spread that were aimed to reduce the infection rate, inadvertently, also lead to the reduction in environmental pollution specifically due to decreased human movement and transportation.

Impact on air pollution:

Chronic exposure to polluted air, especially fine particulate matter (PM2.5), ozone (O3), and nitrogen dioxide (NO2) results in millions of new asthma cases and deaths per year, globally (Achakulwisut et al. 2019). In addition, several studies showed that long-term exposure to polluted air worsens the effects of COVID-19 with increased mortality rates (Benmarhnia, 2020).

Complete or partial lockdowns, stay-at-home orders and social distancing regulations imposed by the governments worldwide, led to a steep decrease in vehicular pollution at the tropospheric and ground levels. It was observed that O3levels were increased because of lower levels of NO2 in the air. These observations were corroborated by several scientists all over the world. For instance, according to a study by Venter et al. 2020, COVID-19 associated lockdowns have resulted in the reduction of NO2 and particulate matter levels by about 60% and 31%, respectively, in 34 countries. However, they observed that the lockdown has mixed effects on ozone. It was inferred that decreased vehicular movements and goods transportation was responsible for decreased emissions. Another study in China (He et al. 2020.) also showed a decrease in air pollution with a significant improvement in the PM2.5 concentrations and the air quality index (AQI) in cities where COVID lockdowns were stringently imposed (Fig. 1). However, it was observed that despite the improvement in PM2.5 and AQI in these cities, the emissions remained four times higher than the WHO recommendations.

Fig. 1: Air quality comparison in the biggest cities around the world before and after the COVID-19 pandemic lockdown (Ref: Saadat et al. 2020)

Similarly, another study (Liu et al. 2020) on daily air pollution across 597 cities worldwide showed a 23 – 37% decrease in NO2, 14 – 20% decrease in PM10, 2 – 20% decrease in SO2, 7 – 16% decrease in PM2.5, 7 – 11% decrease in CO, but a 10 – 27% increase in O3 levels. A study from India (Sharma et al. 2020) conducted during the COVID lockdown showed similar results. 43, 31, 10, and 18% reduction was observed in PM2.5, PM10, CO, and NO2 levels during the lockdown period when compared to previous years. 17% increase in O3and negligible changes in SO2 levels were also observed.

Impact on water pollution:

Decreased industrial activity due to lockdown restrictions has also significantly improved the water quality index (WQI) of water bodies around the world (Chakraborty et al. 2021, Dattagupta et al. 2021, Ormaza-González et al. 2021, Yunus et al. 2020). The restricted flow of tourists to the beaches during the pandemic resulted in amazing transformations with clean water due to decreased pollution in beaches worldwide. It is also noted that the waters flowing in the channels of Venice were cleaner than due to decreased number of tourists (Bhat et al. 2021). However, medical waste comprising of PPE kits, masks, gloves, etc. ended up in oceans and water bodies and pose a serious challenge to the environment (Fig. 2).

Fig. 2: Pictures of medical wastes on a beach shared by Ben Morris (Ref: Kalina et al. 2020)

Impact on noise pollution:

Restrictions due to COVID lockdowns have brought about markedly decreased commercial activity, closure of places of public gatherings like malls, theatres, bars, schools and colleges, sports activities resulted in a significant decrease in the levels of noise pollution across the major cities throughout the world.


Though global lockdown is economically non feasible and practically impossible to execute, nevertheless, COVID-19 pandemic has once again indicated that air pollution poses a significant public health risk and showcased the urgency for an immediate and significant reduction in air pollutants. Finding ways to curb air pollution remains important. Promoting the use of public transportation systems and encouraging the use of clean energy for transportation, industries and households remain the key steps to collectively fight the pollution menace. It also signifies that lockdown measures are economically nonviable to reduce air pollution while many other cheaper ways to achieve the same environmental target exist.



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