Jan 13 2021 Read 467 Times The first COVID-19 lockdowns led to significant changes in urban air pollution levels 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 NO 2 emissions from winter to summer, the researchers evaluated changes in ambient NO 2, O 3 and fine particle (PM 2.5) 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 NO