"It matters more to people right now," says Heming. "COVID is this immediate threat that has made air quality immediately relevant."
That's why she and other indoor air-quality experts say the Biden administration's new National COVID-19 Preparedness Plan is a step in the right direction: It specifically highlights the need to help schools upgrade their ventilation systems for the long term, using funding from the American Rescue Plan Act.
Heming says in the past, it's been hard to make a health case for improving air quality in schools, because the health impacts tend to be longer term. But a whole body of research shows the health and academic benefits are substantial – and go beyond COVID. When a room is better ventilated, influenza rates, asthma attacks and absenteeism go down, reading and math test scores go up. Less carbon dioxide builds up in a room, which helps students think more clearly.
"It's well documented across all different countries and all different ages," says Joseph Allen, director of the Healthy Buildings program at Harvard University. "We see benefits in kindergarteners, we see benefits in high school, we see benefits in college students and middle schoolers – every age group."
Allen says understanding these long-term benefits of upgrading ventilation is vital, "because an investment right now is not just a short-term investment for COVID. If a school does this right, they can expect not only years, but decades of benefits to health beyond reductions in infectious disease transmission."
And experts say those investments are desperately needed, because most U.S. schools are poorly ventilated to begin with. The average American school is over 45 years old, and many have HVAC systems that are outdated or need repairs, according to a 2020 report from the Government Accountability Office. Some schools are so old, they don't even have mechanical ventilation systems.
"I don't think a lot of people recognize that the design standards [that govern ventilation rates in schools and other buildings] are bare minimums. They were never actually set for health," says Allen.
Carl Thurnau knows all too well just how bad deferred school maintenance can get. Several years ago, a classroom ceiling actually collapsed at a school in the City School District of New Rochelle, New York. That's when the district recruited Thurnau, an engineer, to become its director of facilities to oversee a $106 million overhaul of buildings – a process that was already funded and in motion when COVID struck. That money meant the school district could quickly pivot to implement ventilation upgrades in response to COVID.
Having funding in place "is why we were able to get ahead of this – and in my opinion, stay ahead," Thurnau says. But "there's no doubt that districts with less financial resources are struggling to find the money to solve some of these problems."
Ventilation and green building experts have been offering schools guidance on how to improve their air quality to reduce COVID risk since the early days of the pandemic, even before the Centers for Disease Control and Prevention acknowledged the virus could spread through the air. Broadly speaking, Allen says, the advice boils down to three major things: increasing the amount of outdoor air in a classroom; using higher-efficiency MERV filters in HVAC systems; and supplementing these measures with portable air cleaners with HEPA filters.
But two years in, it's unclear how many schools have actually made these changes. That information isn't tracked at the federal level, though some reports hint at the challenges schools have faced. What's clear, says Allen, is that while a lot of schools have taken steps to improve ventilation, many others haven't. "Some haven't done the basic measures, the stopgap measures," Allen says.
Heming says schools have been able to tap federal funds for ventilation upgrades since late December 2020, and the American Rescue Plan Act, passed in March 2021, made a lot more money – $122 billion – available to schools for this and other pandemic-related purposes.
So why have many schools been slow to act when it comes to indoor air quality? Last year, the Center for Green Schools published a survey of more than 47 school districts representing 2.5 million students in 24 states. The vast majority of them said they prefer to invest in long-term solutions rooted in revamping or replacing their HVAC systems.
But with so many old and outdated school buildings, Heming says "these strategies that schools need to use require that they do pretty major renovations."
That kind of work takes many months to plan and contract. In many cases, she says, those plans are only being firmed up now. And a recent survey found many school districts are worried that they won't be able to complete the work by a September 2024 deadline under the law, especially because of supply chain issues and labor and material shortages.
Stopgap measures like opening windows or using portable air cleaners really do work to improve indoor air quality, Heming says, but they can only take schools so far. For example, open windows aren't realistic when outdoor temperatures are freezing, she says, and in humid regions, they can pull in more humidity, promoting the growth of mold.
And while many school districts have invested in stand-alone portable air cleaners, they come with their own headaches, says Heming: The units can be disruptively noisy and they need to be stored and maintained over time.
In general, she says, the school districts that were able to move quickest to improve their air ventilation and filtration in response to the pandemic were those that already had money available to upgrade their facilities, and in many cases, they'd already assessed their buildings and knew which ones needed work.
But there are some encouraging signs that more schools may be catching up soon. An analysis released in February by FutureEd, a think tank at Georgetown University, found that school districts already had plans in place to spend about $4.4 billion on HVAC updates, and if trends continue, that could reach nearly $10 billion. Another FutureEd analysis found that high-poverty districts are more likely to plan to use federal funds to upgrade aging ventilation systems.
The EPA's Tracy Enger says interest in the agency's guidance on indoor air quality for school has skyrocketed over the last year. "What we are seeing is this moment turning into a movement for improving indoor air quality in schools and creating healthier learning spaces," she says.
Heming says she's also optimistic, but her enthusiasm is tempered. She notes that the $122 billion of American Rescue Plan funds designated for schools has to pay for a host of pandemic-related needs – from hiring more staff to summer school programs – not just ventilation upgrades.