Overview

• At least nine states from Michigan and Illinois to Connecticut and Oregon remain under air quality advisories or action-day declarations for unhealthy fine particulate and elevated ozone levels
• Fine particles from over 200 active wildfires in Manitoba combined with ground-level ozone formed by high summer heat are driving hazardous conditions
• Connecticut, Colorado and Oregon issued fresh alerts Thursday, extending warnings into the evening in key counties including Denver metro, southwestern Oregon and Fairfield County
• Health officials urge children, older adults and those with heart or lung conditions to limit outdoor activity, use N95 masks and curb pollution-generating actions such as driving
• Forecasts of scattered storms followed by an approaching cold front may begin to clear smoke and lower ozone concentrations by late Thursday, though agencies will update advisories as weather shifts