In their efforts to combat the spread of Covid-19, schools across the nation have pursued many strategies to improve air quality in their facilities. But many administrators say that those efforts have been hindered by aging and inadequate buildings.
A report from the Center for Green Schools, “Preparation for the Pandemic: How Schools Implemented Air Quality Measures to Protect Occupants from Covid-19,” details the steps schools have taken to reduce the spread of the virus through improved air quality.
But it concludes that in too many of the nation’s school buildings, systems are outdated or not designed to carry out recommended strategies for improving indoor air quality (IAQ).
"School districts still have unmet needs in addressing indoor air quality, in particular, when faced with cost constraints and outdated building infrastructure in the face of changing conditions," the report says. "The most frequently cited challenge to carrying out protective air quality measures at schools was that school buildings were not designed to support the strategies that were being recommended."
The report, completed with technical support from the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE), sought to learn how school districts were prioritizing and carrying out six indoor air quality recommendations for ventilation and filtration to help reduce coronavirus transmission in school buildings. Participants represented 47 districts or independent schools—more than 4,000 schools and 2.5 million students in 24 states.
"Increasing clean air circulation for our teachers and students is vital to promoting public health and is a key green building strategy for school buildings," says Anisa Heming, director of the Center for Green Schools.
IAQ strategies
Taking guidance from numerous sources (e.g., ASHRAE, American Institute of Architects, Centers for Disease Control and Prevention, World Health Organization), the report identifies six major strategies schools have adopted for improving IAQ:
- Increase outdoor air supply through the building’s heating, ventilation and air conditioning system.
- Carry out a flushing process between occupancy periods in which an HVAC system runs for a pre-specified duration or until a target of clean air changes has been reached.
- Open windows to increase the outdoor flow.
- Place fans in windows to exhaust room air to the outdoors.
- Upgrade to filters with higher minimum efficiency reporting values (MERV); MERV 13 or better should be the target for removing airborne viral particles in recirculating systems.
- Install air cleaners with high-efficiency particulate air (HEPA) filters.
More air
Mechanical ventilation strategies—specifically, increasing the outdoor air supply through the HVAC system, and flushing rooms with fresh air before and after they were occupied—were the most commonly prioritized: 89% of respondents aid they prioritized increasing the outdoor air supply, and 79% said they prioritized the flushing strategy.
But respondents also said their efforts to carry out those strategies were hindered by deficiencies in their buildings.
“The number one cited barrier was that at least some of their school buildings were not designed to support (the strategies),” the report states. “Some buildings were so dated that there were no controls to automate….Others mentioned the lack of staff and personnel bandwidth to keep up with the breadth of (indoor air quality) work needed in their school districts.”
Better filtering
Upgrading air filters also has been a popular strategy among schools. The installation of higher-grade MERV filters in at least some of the schools…increased by 120% during the pandemic, the report says.
But again, some schools report that their efforts to upgrade their filters were constrained by the systems and equipment in their buildings.
“Many school districts believed that their existing mechanical systems were too old to be compatible with newer filters,” the report says. “many were concerned that the additional static pressure needed to support the increasing filtration efficiency from either a MERV 8 or 11 to a MERV 13 would overwhelm the system.”
In addition, the high cost and lack of availability of filters (because of high demand) were cited as impediments by respondents.
Opening windows or using fans in windows and doors to increase exhaust were the least popular strategies employed by schools. The study quoted a survey participant: “Opening windows poses safety and air quality concerns from buses and car exhaust in addition to temperature control and noise issues."
Lack of resources
The obstacles to carrying out IAQ strategies and other steps to improve school infrastructure are likely to be more difficult in poorer communities with fewer resources.
“The funding of K-12 education and infrastructure is fundamentally inequitable, given its reliance on local wealth,” the report says. “The pandemic has only served to further entrench those inequities along racial and economic lines. School districts in our cohort that enjoyed a higher-than-average revenue stream remarked at how fortunate they were to have the resources to adapt and pivot as they needed to do.”
Billions of dollars in federal Covid aid earmarked for schools is meant to address some of those inequities.
Keep monitoring
The pandemic has focused attention on the fact that not enough schools were carefully monitoring the air quality in their classrooms and other school spaces. Only two-thirds of survey respondents were regularly monitoring IAQ before the pandemic, an indication that staffing and funding for regular monitoring and data collection has not been a priority for many schools.
On the other hand, respondents indicated that the priority given to IAQ during the pandemic is likely to remain in place. About 70% of the districts responding to the survey say that they plan to continue some or all of the IAQ strategies they have embraced.
"As schools reopen and develop health and safety plans to mitigate airborne transmission of Covid-19, many are prioritizing and upgrading current HVAC systems to provide the highest indoor air quality for building occupants," says Corey Metzger, the lead for ASHRAE's Epidemic Task Force Schools Team.
