<p>The researchers loaded <a href="https://unews.utah.edu/google-cars/">the vehicles</a> with air quality instrumentation and directed drivers to trawl through neighborhoods street by street, taking one air sample per second to create a massive dataset of air pollutant concentrations in the Salt Lake Valley from May 2019 to March 2020. The observations yielded the highest-resolution map yet of pollution hotspots at fine scales—the data captured variability within 200 meters, or about two football fields. Air quality patterns were as expected, with higher pollution around traffic and industrial areas. Pollutants were higher in neighborhoods with lower average incomes and a higher percentage of Black residents, confirming a well-known issue of environmental justice. This pattern traces its legacy to redlining policies from a century ago when the Homeowner’s Loan Corp. created maps that outlined “hazardous” neighborhoods in red ink. </p>
<p style="text-align:start">The authors tested a new atmospheric modeling method with two case studies of well-known pollution sources—a large landfill methane source and a known gravel pit PM<sub>2.5</sub> source. They then applied the model to analyze a previous unknown area of elevated PM<sub>2.5</sub>, located in an industrial area just south of the Salt Lake City airport. </p>