Levels of nitrogen dioxide fell by more than 70 per cent during the lockdown in New Delhi

Levels of nitrogen dioxide fell by more than 70 per cent during the lockdown in New Delhi, a UN policy brief said on Tuesday, warning that the environmental gains could be temporary if the cities re-open without policies to prevent air pollution and promote de-carbonisation.

The UN Secretary-General's Policy Brief on 'COVID-19 in an Urban World' said that with an estimated 90 per cent of all reported COVID-19 cases, urban areas have become the epicentre of the pandemic. It also pointed out that several new scientific studies suggest that poor air quality is correlated with higher COVID-19 mortality rates.

The size of their populations and their high level of global and local interconnectivity make them particularly vulnerable to the spread of the virus.

Levels of nitrogen dioxide fell by more than 70 per cent during the lockdown in New Delhi (India), 40 per cent in urban areas in China, 20 per cent in Belgium and Germany, and 19–40 per cent in different areas of the US," the brief said.

A small increase in fine particulate matter has been associated with an 8 per cent increase and up to 21.4 per cent increase in death rates in the US and the Netherlands, respectively, it said.

New evidence also points to impacts on pregnant women and newborn babies as well as maternal mortality, particularly among populations already facing socio-economic stress due to marginalisation.

On COVID-19 outbreaks in informal settlements, the brief said that in Mumbai, as of mid-April 2020, 30 per cent of designated containment zones — which are areas with large outbreaks — were in slums, while 60 per cent were within 100 metres of an informal settlement, it said.