A new study found that exposure to wildfire smoke in the last summer's wildfire season could lead to thousands more coronavirus infection and hundreds of deaths.Wildfire smoke is high in PM 2.5, the smallest and most dangerous form of soot.Harvard University researchers estimated that wildfire smoke exposure caused nearly 20,000 additional coronavirus cases and 750 Covid-19 death between March 2020 and December 2020 in the American West. Science Advances published the paper on Friday.Smoking, whether it is from cigarette smoke or air pollution, can cause a decrease in white blood cell function and a reduction in immune system response. Particulate matter and chemicals can also cause inflammation of cells in the lungs and airways. Researchers say that both cases can lead to an impaired immune response, which could result in a person developing a more severe condition than they would otherwise.These findings add to the already established connection between air pollution, respiratory-tract infections, and asthma. The study is the first to establish a statistical connection between wildfire smoke, Covid-19 caseloads, and deaths.