With millions more working from home and fewer people taking daily commutes in cars, you might assume pollution levels in cities dropped dramatically during the pandemic restrictions of 2020. But new research shows the impact was far less pronounced than initially thought, and air pollution in cities around the world declined less than expected during the first widespread lockdown restrictions of early 2020. It had previously been reported, for instance, that the NO2 level in Wuhan, the Chinese city where the virus was first detected, dropped by 93 per cent during its lockdown. However, when w...