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Schools aren’t following air quality recommendations to reduce COVID-19 risk, DMN finds

Experts recommend good ventilation, filters and other measures.

Improving ventilation and air quality is one method that schools can take to lower the risk of COVID-19 transmission, scientists say.

Yet, in a survey of large school systems in North Texas, The Dallas Morning News found that schools fell short of air quality guidelines released in June by building experts.

Researchers from Harvard University recommended high-rated air filters, portable air cleaners, and ultraviolet light inside air ducts to help eliminate the virus. Carbon dioxide checks in classes full of students can show if enough fresh air is getting in.

The News asked a dozen area school districts, as well as the Catholic Diocese of Dallas, about their air filtration and monitoring, and did not find a school that met all the recommendations set out by Harvard’s researchers. Three school districts did not respond to multiple requests: Allen, Arlington and Grand Prairie.

Indoor air quality has been a problem in America’s K-12 schools for decades. Aging buildings tend to be worse.

Said Hobie Hukill, a 69-year-old educator in Dallas and a librarian at Samuell High School for the past decade: “There hasn’t been a time when our HVAC system didn’t have something wrong with it.”

Evidence points to three routes of transmission of the virus: touching contaminated surfaces and then your face; taking in droplets at close range; and inhaling smaller airborne particles of the virus from a distance.

Masks that cover the nose and mouth can reduce the amount of virus exhaled by someone who is infected.

But masks aren’t perfect barriers, said Richard Corsi, a former engineering professor at the University of Texas in Austin who’s now a dean at Portland State University in Oregon. And, a person who is infected will breathe out a plume of infectious particles.

Adding good ventilation to classrooms can counter the airborne route of transmission, Corsi said. But typical ventilation systems can’t remove the exhaled virus before it naturally deactivates.

That “basically means that the majority of infectious viruses in these droplets will remain infectious as long as the air is in the building,” Corsi said.

Air filters are rated, from 1 to 20, based on their filtration effectiveness, or Minimum Efficiency Reporting Value (MERV). The higher the MERV rating, the better the filter traps smaller particles.

According to the National Air Filtration Association, MERV 13 filters — the type recommended by the Harvard researchers — are typically used for hospital, surgery and health care facilities, smoke removal, and as the “superior” option for commercial buildings.

No area schools were using MERV 13 filters, although Frisco ISD and the Catholic Diocese said they had some on order. Most of the schools used filters ranging from MERV 8 to MERV 11, which would trap things like mold spores and dust, but not COVID-19.

All the school systems said they monitored carbon dioxide. Most — including Garland, Frisco and Highland Park ISDs — relied on classroom or campus sensors to check levels regularly. Dallas ISD monitors those levels “if there is an air quality concern at a school or facility,” district spokeswoman Robyn Harris said.

At the time of the survey, no school systems were using ultraviolet irradiation on their campuses, although Matt Vereecke, superintendent of Catholic schools for the Diocese of Dallas, said ultraviolet light devices would be installed at some of the diocese’s 33 facilities.

Corsi has studied air exchange rates in Texas classrooms and said it’s generally low.

“Going back to school in a place that’s a hot zone, it’s basically asking for trouble,” he said.

Corbett Smith. Education writer (and part-time HS sportswriter) for The Dallas Morning News

corbettsmith@dallasnews.com /DMNEducation @corbettsmithDMN

Sue Ambrose. Sue Ambrose has worked as a reporter for The Dallas Morning News since 1995. A member of the investigative team since 2008, she has reported on hospital safety, mismanagement at state agencies and misspending of public funds. She began her journalism career covering science.

sambrose@dallasnews.com /sue.g.ambrose @bysambrose
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