Freshmen head to classes on their first day of in-person school at McKay High School on Tuesday, April 13, 2021. (Amanda Loman/Salem Reporter)

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Hundreds of freshmen streamed onto the South Salem High School football field around 8:30 Tuesday morning, flanked by upperclassmen welcoming them with blue, red and white pom-poms.

The start of school assembly is the sort of the event that might typically have been held in the school gym before Covid, but was outside to allow for better airflow and more space between students.

On Wednesday, nearly 40,000 kids head back into classrooms in Salem as Oregon’s second-largest school district begins classes. Tuesday was an early start for sixth and ninth graders, allowing them to get schedules and learn their way around buildings in a less chaotic environment.

As Oregon has reported record levels of new Covid cases and hospitalizations, keeping the virus from spreading at school has been a central concern of public health authorities and many school districts.

Oregon schools reported few Covid outbreaks in the spring after most resumed classes, though local schools had significantly fewer students in buildings because of capacity restrictions.

In Salem-Keizer, several schools reported multiple cases of Covid among both students and employees, but district officials said those typically involved students who also spent time together outside class. None grew into larger outbreaks which required schools to close.

While Gov. Kate Brown’s requirement that students, educators and volunteers wear masks inside schools has received the bulk of the attention - and pushback - as classes resume, masking isn’t the only thing happening in Salem schools.

Here’s where the district stands on other best practices to prevent the spread of Covid inside schools.

Ventilation systems

Good ventilation that prevents virus particles from circulating in the air is key to preventing Covid from spreading indoors, according to the Centers for Disease Control and Prevention.

In the Salem-Keizer School District, building HVAC systems have been optimized to maximize the amount of air coming into buildings from outside, rather than recirculating indoor air.

Air inside buildings is refreshed at least three and five times per hour, said Mike Wolfe, chief operating officer for the district.

While neither state nor federal guidelines specify an air refresh rate schools should aim for, both say more frequent movement of air is an important part of ensuring viruses don’t linger in schools.

School HVAC systems are also operated for two hours before and after buildings are occupied for the day to “purge” the air - something also recommended by the CDC.

Some school buildings have received recent HVAC upgrades as part of school construction planned prior to the Covid pandemic.

In March 2021, the district revised its HVAC operating guidelines, saying it would assess buildings where system upgrades were needed and develop a timeline and plan to update those systems.

District officials have not yet provided a copy of that plan or a list of schools where upgrades have taken place in response to a Sept. 1 request from Salem Reporter.

"We have many upgrades under construction at this time. We will be continuing to evaluate buildings to determine where upgrades would be warranted," said Joel Smallwood, district manager of construction and maintenance services, in an email. 

On Friday, the district changed its policy on windows, saying teachers and school staff can leave outdoor windows open during the day to improve air circulation. That’s in line with state and federal recommendations to improve airflow.

Previously, district policy had discouraged teachers from opening windows because it makes it more difficult for building HVAC systems to maintain temperatures inside. The change was made after a review of district protocols ahead of school starting, district spokesman Aaron Harada said.

Air filtration

Federal and state authorities say schools should use air filters that can trap virus particles where possible as part of their HVAC systems.

Filters are rated on a scale called Minimum Efficiency Reporting Value, or MERV, with a value from 1 to 20. A higher number means the filter can trap smaller particles.

The federal Environmental Protection Administration says filters rated MERV 13 and higher can generally capture virus particles.

The Oregon Department of Education recommends schools increase air filtration to MERV 13 where possible, or else use the highest filtration level the system allows.

Salem-Keizer schools’ HVAC systems typically operate best with MERV 8 or MERV 11 filtration, Wolfe said in an email.

“Simply increasing the MERV filters to a 13 would significantly degrade the system performance at most if not all of our buildings,” he said.

Wolfe said the district’s approach is to “optimize system performance at each building. Each system is unique to the time it was installed and/or upgraded over the years to meet the current code requirements at that time.”

He said the district is working on a comprehensive HVAC assessment using federal relief funds, but has been challenged because of “significant supply chain issues associated with HVAC system components.”

To improve air filtration, about 600 HEPA portable air filters have been deployed to buildings around the district, Harada said. Those filters are prioritized for spaces at higher risk of Covid spread, such as classrooms without windows, areas like front offices where many people come and go during the day, Covid isolation rooms and locations where students receive medical treatment.


School meals are a particular concern for the spread of airborne viruses, since students need to remove masks to eat, and meals usually mean more students in the cafeteria at one time.

The approach to meals will vary by school, Harada said, depending on building layout and safety concerns, but he said in general schools are using classrooms, outdoor areas or other non-cafeteria spaces for lunch in addition to the cafeteria so students can spread out more.

Some high schools have added extra lunch periods to reduce the number of students eating at any one time, Harada said.

Students are supposed to remain at least three feet apart during meals and keep masks on until they’re seated and eating, he said. Cafeterias are also cleaned and sanitized after use.

Parents with questions or concerns about lunch should contact their child’s school, Harada said.

Covid testing

The district has BinaxNOW rapid Covid antigen tests available to screen employees or students who develop symptoms of illness at school, Harada said. Student tests require permission from a parent or guardian.

School districts in Oregon can opt to offer weekly surveillance testing of both unvaccinated employees and unvaccinated students through partnerships with the Oregon Department of Education and Oregon Health Authority.

Surveillance testing means widespread testing of people without symptoms of Covid and is intended to detect infections earlier, helping to prevent the virus from spreading.

Harada said the district is working on a plan for Covid screening options for students with the Oregon Health Authority, but has not yet finalized it.

Contact reporter Rachel Alexander: [email protected] or 503-575-1241.

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