Historic Trends for Fine Particles (PM2.5)

Wisconsin Department of Natural Resources began monitoring for fine particles in 1997, with our initial efforts focused on the urban areas in Milwaukee and Waukesha counties and near the Illinois border. The network expanded across the state and now incorporates manual sampling every three days as well as continuous monitoring at 10 sites. Although particulate pollution may be worse in metropolitan areas, our rural sampling sites show similar patterns as Madison and Green Bay and air quality can move into the Unhealthy for Sensitive Individuals range at any time during the year. In some areas, it appears that the percentage of good days is increasing while it's declining in others.