Researchers published an article in the October edition of European Review of Medical and Pharmacological Sciences, looking at the impact of wildfire smoke on COVID-19 in San Francisco. The researchers looked at daily COVID-19 cases, deaths, particulate matter (PM-2.5 μm) and carbon monoxide from March 20, 2020 to Sept 16, 2020. They found that a one micrometer (μg/m3) increase in PM2.5 were associated with an increase in the daily COVID-19 cases, cumulative cases and cumulative deaths by 0.5%, 0.9% and 0.6%, respectively. Additionally, with a 1 part per million (ppm) increase in carbon monoxide level, the number of daily COVID-19 cases, cumulative cases and cumulative deaths increased by 5%, 9.3% and 5.3%, respectively. They concluded that, “The wildfire allied pollutants, particulate matter PM-2.5μm and CO have a positive association with an increased number of SARS-COV-2 daily cases, cumulative cases and cumulative deaths in San Francisco.”