Today’s Guardian reports on research published in the journal “Science of the Total Environment,” which shows that almost 80% of deaths across four countries were in the most polluted regions. The research examined levels of nitrogen dioxide, a pollutant produced mostly by diesel vehicles. “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, at Martin Luther University Halle-Wittenberg in Germany, who conducted the research. Professor Jonathan Grigg, from Queen Mary University of London, said the study showed an association between Covid-19 deaths and NO2 levels. The article states that long-term exposure to dirty air before the pandemic may be more important than current levels of pollution.