The Montana Department of Environmental Quality issued an air quality alert for Lewis and Clark County on Saturday, July 26, with the advisory running through 9 a.m. Sunday, July 27. The National Weather Service office in Great Falls relayed the alert at 8:55 a.m. MDT. Eleven Montana counties are covered, stretching from Missoula and Ravalli in the west to Hill, Liberty, Toole, and Pondera in the north.
The alert means particulate levels have been trending upward and that the 24-hour National Ambient Air Quality Standard — the federal threshold set by the EPA — has been exceeded or is at risk of being exceeded. Fine particulate matter from wildfire smoke is the most common driver of summertime exceedances in western Montana, and the multi-county footprint of this alert is consistent with a regional smoke event rather than a localized source.
Helena residents who are sensitive to air quality — including people with asthma, heart or lung conditions, the elderly, and children — are advised to limit time outdoors and keep windows closed during the alert period. The DEQ recommends checking AirNow.gov for real-time air quality index readings specific to the Helena monitoring station before planning outdoor activities.
The alert expires Sunday morning, but conditions can shift quickly depending on wind direction and fire activity. Anyone with health concerns should monitor DEQ and NWS updates through the weekend.