UNITED NATIONS : 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.