High levels of air pollution may be one of the most important contributors" to deaths from Covid-19, according to research. The analysis shows that of the coronavirus deaths across 66 administrative regions in Italy, Spain, France and Germany, 78% of them occurred in just five regions, and these were the most polluted. The research examined levels of nitrogen dioxide, a pollutant produced mostly by diesel vehicles, and weather conditions that can prevent dirty air from dispersing away from a city. Many studies have linked NO2 exposure to health damage, and particularly lung disease, which could make people more likely to die if they contract Covid-19. "The results indicate that long-term exposure to this pollutant may be one of the most important contributors to fatality caused by the Covid-19 virus in these regions and maybe across the whole world," said Yaron Ogen ... who conducted the research. A separate study published on 7 April looked at fine particle pollution in the US and found that even small increases in levels in the years before the pandemic were associated with far higher Covid-19 death rates. Another recent paper noted that the high death rates seen in the north of Italy correlated with the highest levels of air pollution. Jenny Bates, an air pollution campaigner at Friends of the Earth, said: "This new study is worrying. This is all the more reason to keep traffic and pollution levels down as much as possible now and get out of this terrible situation with a view to fewer but cleaner vehicles on the road."