Early responses to the Covid-19 pandemic led to dramatic reductions in air pollutant concentrations in many locations worldwide. Research has suggested that significant health benefits could be realised if these air pollution reductions remain in the long-term after government restrictions are relaxed. In this report, investigate nitrogen dioxide (NO2) pollution data from ground level monitors and satellite observations. The analysis compares air quality before the emergence of Covid-19 against pollution measurements made during different stages of the pandemic. Ground level measurements of fine particulate matter (PM2.5) were also analysed in those locations where data were readily available. Weather conditions can hide or exaggerate the effect of changes in emissions on air quality; therefore a statistical technique is used to account for the effect of weather in different time periods.
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