https://www.mercurynews.com/2021/08/24/lake-tahoe-air-quality-reaches-hazardous-levels-from-wildfire-smoke/

HOMEWOOD — The Lake Tahoe area reported the worst air quality in the nation Tuesday as wildfire smoke spread north from the Caldor Fire and settled over communities along the lake’s western shore.

AirNow, which monitors the amount of fine particulate matter affecting air quality across the U.S., reported figures ranging from the 400s in the Truckee area all the way to 559 in Homewood north of Sugar Pine Point State Park — a number so high it surpassed the monitor’s usual scale.