Portland Public Schools said on Friday that it will attempt to heed a state recommendation for at least three air changes per an hour. (Beth Nakamura/The Oregonian/File photo)LC-

In a sweeping about-face, Oregon’s largest school district on Friday said it will “strive” to increase a key measure of air quality to minimum levels long-trumpeted by a wide swath of experts nationwide.

Portland Public Schools’ announcement comes after an investigation by The Oregonian/OregonLive in May found nearly 500 classrooms with subpar ventilation rates. Experts said those ventilation levels could increase the risk of airborne-disease transmission as well as lower the ability of students to think and learn in classrooms with stale air.

The district’s announcement also comes on the heels of clarified COVID-19 guidance from the Oregon Health Authority, brought about by questions raised by The Oregonian/OregonLive earlier this month. On Thursday, the health authority told school officials it “recommends a range of 3-6 air changes per hour” in classrooms and other “public indoor spaces,” along other strategies to improve air quality.

Air changes measure the number of times a room’s total volume of old, stale air is replaced by fresh air within an hour’s time.

It’s a key component of gauging indoor air quality, many experts say, but one that the district has rejected as a metric it should endeavor to meet. One of the district’s top officials, chief of staff Jonathan Garcia, said that has now changed.

“In light of the Oregon Health Authority’s (OHA) clarification and recommendation on September 22, we are confirming that PPS will strive to make any necessary changes to increase the air change per hour (ACH) to more than three in the classrooms where that isn’t already happening,” Garcia said in an email late Friday to The Oregonian/OregonLive.

Precisely how the district will work to improve fresh or filtered air into classrooms -- or the timeline for doing so -- was not immediately clear. Upgrades could conceivably come in the form of adding more portable air purifiers.

Portland Public Schools bought air purifiers in 2021 for all of its student- and staff-occupied spaces. But even with the purifiers running full speed, nearly 500 K-8 classrooms didn't meet minimum recommendations, according to data from district reports. Worsening the numbers, teachers often run the purifiers the district bought at half speed because they say they are too loud. (Courtesy to The Oregonian)Courtesy to The Oregonian

Friday’s announced action is expected to affect nearly 25% of the district’s elementary and middle school classrooms, where room-by-room measurements from last year showed air changes hovering below three an hour. It’s unclear if the district plans to increase ventilation to the same level in the more than 50% of cafeterias, gyms and libraries across all grade levels that failed to reach three air changes per an hour. The health authority told The Oregonian/OregonLive that its recommendation applies not just to classrooms, but to other indoor spaces in schools, as well as buildings such as restaurants, grocery stores and workplaces.

Garcia did not return a request for more information late Friday.

Garcia said in an email that district officials remain confident air quality in classrooms is already safe. He suggested that in aiming toward a minimum number of air changes, the district might not know if it’s achieved that in all spaces.

“Practically speaking, we don’t have the means to measure ACH (air changes per hour) in every learning space on a regular and ongoing basis,” he wrote. “For this reason, we will continue to follow OHA’s core advice – to employ a layered mitigation approach.”

Garcia’s late afternoon email capped a dizzying week for the district, which for well over a year has lauded its work in improving indoor air.

The district has made praiseworthy strides toward that end. It spent more than $5 million to upgrade HVAC filters in buildings and buy portable air purifiers for all student- or staff-occupied spaces, including all classrooms, cafeterias and offices.

Last school year, the district also took the unusual step – one commended by experts – of measuring the air changes per hour in each one of those spaces at a cost of about $800,000. But the survey exposed some widespread deficiencies in the district’s ventilation, according to outside experts. The district, however, didn’t see those as problems – and pushed back on the notion that it should increase air changes per an hour in those poorly ventilated spaces.

The Oregonian/OregonLive interviewed more than a dozen air scientists and ventilation professors from top universities and institutions across the country who said three should be the “bare minimum.” Many said anything below that was concerning, and schools should aim higher to try to reduce the increased risks that can come with stagnant air. The vast majority of experts queried said at least five or six air changes should be the goal.

Last year, in a document titled “COVID-19 Public Health Recommendations,” the Oregon Health Authority also published similar recommendations from two universities with respected departments in air and building sciences. But an agency spokesperson said that was not an official recommendation.

That changed this month, when The Oregonian/OregonLive questioned the agency’s deputy state epidemiologist, Dr. Ali Hamade. He clarified it was the authority’s recommendation. The news organization presented that information to the school district, prompting the district to contact the authority for clarity, because the district has said it will follow recommendations from public health agencies.

This “contradicts what you shared with me earlier in the week that the ‘OHA is not specifically recommending 3-6 air changes per hour in classrooms,’” Garcia wrote to a senior policy adviser at the authority in a letter Monday.

Garcia asked the agency to clear up any “ambiguity or conflicting language” that “leads to media coverage or a level of public mistrust” by explaining if the agency indeed was recommending at least three air changes.

That prompted Rachael Banks, the state’s public health director, to write her letter Thursday confirming the health authority “recommends a range of 3-6 air changes per hour.”

But the letter also made clear those ventilation rates should be accompanied “along with” other measures to reduce disease transmission, including wearing masks, opening windows when safe and positioning fans in windows to blow indoor air out and outdoor air in.

School board member Julia Brim-Edwards, who is a member of a district committee that met Thursday to discuss air quality, noted that the district lifted the indoor mask mandate in March, days after Gov. Kate Brown did. She said some windows also don’t open. She asked whether district leaders believe – in the absence of following minimum air-change recommendations – that remaining disease-safety protocols are enough to ensure the air is safe.

Doug Hancock, an air quality investigator hired by the district, said yes. He cited an important protocol that still remains in place: Asking sick people who are showing symptoms to stay home.

In the Oregon Health Authority’s letter to the school district Thursday, Banks acknowledged the challenges of improving ventilation.

“It is conceivable that not all institutions are able to achieve 3-6 of air changes per hour,” Banks wrote. “Having a lower number of air changes does not mean an automatically increased risk of disease transmission.”

She added: “This depends on the other layers mentioned above, community transmission rates, vaccination status, previous infection, and others.”

School districts are left to set their own standards because no local, state or federal agency sets requirements for air changes. But it’s notable that a committee of ASHRAE, the industry group of engineers that sets ventilation standards for buildings, has said schools should ideally aspire to six to eight air changes an hour.

Nationwide, experts say it’s common for schools and other buildings to have low ventilation rates. But districts across the country have been flush with federal coronavirus relief money, and at least some have set loftier airflow goals. Washington, D.C., and Seattle are among those pursuing higher rates.

As recently as last spring, many suburban Portland school districts also had taken notice of experts’ air-change recommendations. Eight of the 12 largest adopted air-change-per-hour goals that exceed bare minimum targets. That includes Beaverton at five and Hillsboro at six, The Oregonian/OregonLive’s investigation found.

-- Aimee Green; agreen@oregonian.com; @o_aimee

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