Allegheny County Health Department Issues Mon Valley Episode Watch Due to Air Quality Alert

The Allegheny County Health Department has issued a Mon Valley Episode Watch for Tuesday, October 20, 2026, coinciding with the Pennsylvania Department of Environmental Protection's Code Orange (Unhealthy for Sensitive Groups) Air Quality Alert for the Monongahela Valley. High pressure is expected to limit air mixing, trapping pollutants close to the surface for several morning hours, potentially resulting in air quality in the Code Orange or higher range.