San Francisco Unified School District officials are looking into spending $2.9 million on portable air purifiers to combat poor air quality from wildfires.

Most classrooms rely on open windows to prevent the spread of COVID-19 — a main concern as in-person learning resumed just last week — but unhealthy air is making that difficult.

The district’s current guidelines call for all school sites to have an operable window, a portable air purifier, or a mechanical ventilation system to ensure air flow.

District staff have been examining ventilation systems inside classrooms since the start of the year, as some elementary schools reopened for in-person learning in April, and throughout the summer.

Currently, just 10 percent of the district’s 3,063 classrooms have district-provided portable air cleaners, which meet the district’s wattage and air filtration standards.

“SFUSD has already distributed 775 portable air cleaners to ensure classrooms without sufficient operable windows or mechanical air systems have adequate ventilation,” Superintendent Dr. Vincent Matthews said. “With increased concerns about managing indoor air quality in light of wildfires and COVID and given our early tests, we have been preparing to purchase even more portable air cleaners.”

The purchase of the extra air cleaners will first need to be approved the San Francisco Board of Education. Once approved, district officials plan to distribute them as soon as possible, on a rolling basis.

District officials said the district is not accepting donations of portable air purifiers but donations to help the purchase of more air cleaners, and to support the district’s other initiatives, can be made online.