Early COVID-19 lockdown had less impact on urban air quality than first believed
January 18 - February 28
The first COVID-19 lockdowns led to significant changes in urban air pollution levels in major cities around the world, but the changes were smaller than expected – a new study reveals.
After developing new corrections for the impact of weather and seasonal trends, such as reduced NO2 emissions from winter to summer, the researchers evaluated changes in ambient NO2, O3 and fine particle (PM2.5) concentrations arising from lockdown emission changes in 11 global cities: Beijing, Wuhan, Milan, Rome, Madrid, London, Paris, Berlin, New York, Los Angeles and Delhi.
Led by experts at the University of Birmingham, the international team of scientists discovered that the beneficial reductions in NO2 due to the lockdowns were smaller than expected, after removing the effects of weather. In parallel, the lockdowns caused (weather-corrected) concentrations of ozone in cities to increase.
NO2 is a key air pollutant from traffic emissions, associated with respiratory problems, while ozone is also harmful to health, and damages crops.