Swirling smoke from California’s historic firestorm is still clogging some of the state’s skies — leading to unhealthy air quality in and around the Sierra Nevada.

Conditions at one point were considered hazardous Monday morning in the area of Mammoth Lakes, meaning “everyone should stay indoors and reduce activity levels,” according to air quality monitors.

However, the air later cleared to a point where it was only “very unhealthy,” with residents urged to avoid strenuous outdoor activities.

That part of California has been subjected to particularly foul air quality. Some areas around Bishop and Mammoth Lakes were listed as “beyond index” last week — with air quality measurements that reached 626, far beyond the 0-500 scale.

Read the full story on LATimes.com.