The EPA had some money from the recovery funding and then the inflation reduction act to do more air quality monitoring stations - the EPA gave out 132 awards around the country, my city got one and we're putting up 68 sensors around town (one in each census tract) - the program and the awardees are here, if you're interested in seeing if your city got one:
https://www.epa.gov/arp/arp-enhanced-air-quality-monitoring-...
(My city is using QuantAQ sensors, which weren't cheap)