The Montana Department of Environmental Quality (DEQ) has developed a program called PurpleAirs in Schools, a state-wide air quality monitoring system at high schools across the state. The program includes hundreds of low-cost, effective, air quality sensors installed at schools and tracks PM2.5, tiny, inhalable particles that are hazardous to human health and associated with wildfire smoke. The project is funded by a federal grant and includes the Montana High School Association and the University of Montana. The sensors are not required to be installed, but the program has become nationally notable. About two-thirds of school communities in Montana have signed up for sensors, and the state is working to get the remaining districts into the program.