The widespread lockdown caused by the novel coronavirus pandemic has resulted in major falls in air pollution levels as restrictions on travel saw fewer vehicles on the roads and planes in the air.
Satellite images have revealed dramatic reductions in concentrations of pollutant nitrogen dioxide, or NO2, in China and Northern Italy, coinciding with localized lockdowns.
According to experts at the University of York in the United Kingdom, air pollution levels in some UK cities have dropped to levels lower than the average of the previous five years.
Data from roadside monitoring sites in York, Birmingham, Glasgow, London and Manchester show a reduction in NO2, a pollutant mainly emitted from vehicle exhausts.
James Lee, a professor of atmospheric chemistry at the University of York, said he has seen an NO2 reduction of 30 to 50 percent.
NO2 and fine particles known as PM2.5 are the two air pollutants that have the biggest impact on people's health in the UK.
Lee said the data could be an indication of what cities may be like in 20 years' time, when more electric vehicles will be in use.
Air pollution causes an estimated 40,000 premature deaths in the UK each year, and it is linked to health problems including strokes, heart disease, lung problems including cancer, and respiratory diseases and infections, as well as stunting the growth of children's lungs.
As Britain remains in lockdown to stop the spread of the novel coronavirus, Lee expects to see NO2 levels change further in the coming weeks, depending on the weather.
While the drop in NO2 level is likely to be caused by less traffic in the cities, the sources of particulate matter, or PM2.5, are more varied but include pollutants from road transport, industry and fuel burning.
"We can say for sure that NO2 has dropped but the particulates are a more complicated story because they come from a wider variety of sources. This does show that even with an electrified vehicle fleet in the future, that doesn't put us out of the woods when it comes to air pollution, there are other factors that we need to consider going forward," Lee said.
Scientists have said they will continue to track NO2 levels and other sources of pollutants to be able to identify the exact cause of pollution.
"I'd like to think there would be a social change with people realizing how much work can be achieved by not travelling, not going to so many meetings, and doing them remotely. As things start to be relaxed and the restrictions removed, then longer term, we will start to dig deeper into the data, specifically particular matter."
