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NASA estimates show that ozone pollution levels in May-June 2020 decreased by 2%, largely due to reduced emissions in Asia and the United States. While this may not seem like a large number, experts say this reduction is equivalent to at least 15 years of implementing the best emission reduction policies recommended by the Intergovernmental Panel on Climate Change.
Ozone in the upper atmosphere helps shield our planet from harmful radiation from the Sun. But in the lower atmosphere, ozone can cause respiratory discomfort and increase mortality rates from cardiovascular and respiratory diseases. Ozone is not a direct human-generated waste product; it is created when light interacts with nitrogen oxide (NOx) molecules emitted from vehicles, factories, power plants, and smelters.
NO2 levels in Europe decreased significantly after lockdowns were implemented due to Covid-19.
Scientists have realized that the social distancing campaign over the past year presented an opportunity to observe what would happen to the atmosphere if human activity and emissions were drastically reduced. This could then lead to the development of more effective environmental solutions.
By feeding data from multiple satellites in 2020 into four models predicting atmospheric response, researchers at NASA found that NOx emissions fluctuated with intensity related to isolation events. In April and May, global emissions decreased by at least 15%.
Countries with the strictest lockdown policies saw the highest reductions in emissions. For example, in China, lockdowns implemented at the beginning of the year helped the country reduce emissions by up to 50%. In regions that implemented lockdowns later, such as the US, Europe, the Middle East, and West Asia, NOx emissions decreased by approximately 18-25% in April and May.
The impact on the atmosphere occurred on a large scale and with surprising speed. Following the lockdown, data showed a dramatic global reduction in ozone, purifying the air at altitudes up to 10 km. In the troposphere, ozone not only degrades air quality but also plays a role in trapping heat and increasing global warming.
Scientists believe the pandemic has brought many benefits to air quality and climate change. However, without maintaining the measures taken so far, these benefits may not be significant. And as the world reopens, ozone levels will undoubtedly increase proportionally with the increase in emissions.
