Nitrogen dioxide (NO2) is one of the six common air pollutants that the U.S. Environmental Protection Agency (EPA) classifies as ‘criteria air pollutants’. Excessive exposure to NO2 can exacerbate respiratory diseases such as asthma, causing symptoms such as coughing and wheezing that can damage the lungs. In addition, the interaction of nitrogen oxides with other chemicals in the atmosphere produces acid rain, particulate matter, and ozone, which are major contributors to deteriorating air quality in urban and industrial areas. To map NO2 from space and on the ground, the authors used measurements from the European Space Agency (ESA) TROPOMI (TROPOspheric Monitoring Instrument) satellite and the U.S. EPA. These measurements were used to examine how reductions in activity related to COVID-19 impacted tropospheric NO2 in Houston, Texas.