Nitrogen dioxide is a chemical byproduct of fossil fuel combustion and contributes to smog, acid rain and has been linked to human asthma and other respiratory illnesses. Since 2005, the National Aeronautics and Space Administration has been observing nitrogen dioxide levels across the globe. In March, 2020, the NASA satellite noted the lowest NO2 emissions over the northeastern portion of the United States it had ever recorded — 30% lower than the previous year’s. These observations came as most of the northeastern states were under lockdown, with all but essential travel curtailed, under public health orders designed to combat the COVID-19 virus. Scientists have observed other environmental effects of the forced reduction in human activity. University of Wisconsin – Madison Professor of Atmospheric and Oceanic Sciences Ankur Desai joined Monday Buzz host Brian Standing on April 27, 2020.