Monthly nitrogen dioxide concentrations in select cities in the UK 2020
On March 23, 2020 the UK entered its first national lockdown in a bid to curb the spread of COVID-19. The lockdowns saw a significant decline in road traffic in major cities across the country, leading to a reduction in concentrations of nitrogen dioxide (NO2) - a pollutant mainly emitted by road transport. In London, concentrations of NO2 fell to a low of 17.5 ug/m3 in July, while levels in Liverpool dropped to 15.7 ug/m3 in May.
