Thousands of New York City classrooms have been cleared as having adequate ventilation for safe, in-person instruction even though they do not meet the COVID-19 standards set by federal experts or recommended by building industry experts, WNYC/Gothamist has found.
A simple, green checkmark indicates whether “operational ventilation” is available in one of the 58,600 classrooms surveyed by the city’s Department of Education (DOE). As of August 29th, officials have awarded this seal of approval to 97% of these classrooms.
But the DOE classifies at least 4,000 of these approved classrooms as relying exclusively on functioning windows—a lower standard than what would be expected to prevent airborne transmission of the coronavirus indoors. If these window-only rooms lost their “operational” status, it would triple the number of classrooms currently ineligible for in-person learning this fall.
“Windows are not a reliable way for you to get outside air,” said Dr. Marwa Zaatari, a mechanical engineer and member of the Epidemic Task Force of the American Society of Heating and Air-Conditioning Engineers (ASHRAE), which is cited in Centers for Disease Control and Prevention recommendations for schools and other buildings. “Is it better than zero? Yes. But, as a ventilation engineer, can I predict how much [fresh] air you're getting at each hour of the day? The answer is no.”
Given that aerosolized particles with SARS-CoV-2, the virus that causes COVID-19, can remain suspended in the air for long stretches of time, ventilation and air purification represent key preventative strategies. In its guide to opening schools, the Centers for Disease Control and Prevention (CDC) recommends schools consider adding portable air purifier units with high efficiency particulate air (HEPA) filters to “enhance air cleaning wherever possible.” The CDC’s FAQ on ventilation notes, “Portable HEPA filtration units that combine a HEPA filter with a powered fan system are a preferred option for auxiliary air cleaning.”
An investigation by The Classic has found that, though it has told the public that two “HEPA Purifiers” will be in each classroom this fall, the New York City Department of Education (DOE) will be providing devices (Intellipure compact air purifiers) that do not match that description. The DOE has repeatedly referred to the Intellipure units as “HEPA purifiers” on its website, in a “DOE Homecoming Health and Safety Guide,” and in statements to The Classic. Multiple experts have told The Classic that to be a “HEPA Purifier” the units should have within them an actual HEPA filter, but they do not.
When asked by The Classic to comment on the accuracy of the DOE’s decision to describe the Intellipure units as “HEPA purifiers,” DOE spokesperson Nathaniel Styer said, “We never said that the units had HEPA filters. We said that they met the standard for HEPA filtration. That they are HEPA purifiers.”
On Twitter, Mr. Styer claimed that HEPA refers to a rating that could be applied to “different types of machines” that filter particles at the level of HEPA filters. According to the Environmental Protection Agency, the designation HEPA is specifically applied to “a type of pleated mechanical air filter” tested to a standard level of efficiency. Citing the CDC, Mr. Styer said that because Intellipure’s process as a whole can filter at HEPA filter levels, it is a HEPA purifier. The Classic contacted the CDC, however, and a representative said the two technologies are distinct.
“The distinction between an air cleaner using a true high-efficiency particulate air (HEPA) filter and one that does not should be clear,” said Dr. Steve Martin, an engineer and expert on ventilation at the National Institute of Occupational Safety and Health, a branch of the CDC, in an email to The Classic.
Dr. Martin said that while “it is certainly possible for other air cleaners to use a combination of filtration technologies that can perform at ‘HEPA-equivalent’ levels (and maybe even higher),” the Intellipure air purifiers are not true HEPA devices. “The distinction should be clear between true HEPA air cleaners and others,” he said.
The difference between a true HEPA filter and a HEPA-equivalent device can be significant, according to Dr. Martin. “The biggest concern with air cleaners claiming ‘HEPA-equivalent’ performance is how they perform over time. As a true HEPA filter loads with particles over time, the overall filtration efficiency will only increase. The same can not necessarily be said for other technologies,” he said.
Other experts spoke to The Classic about whether it was accurate for the DOE to describe the Intellipure units as HEPA purifiers to the public.
“HEPA refers to having a specific type of filter… so a product should have one of those filters in it to be a HEPA purifier,” said Dr. Delphine Farmer, an atmospheric chemist with a research focus in air pollution from Colorado State University, in an email to The Classic.
According to an email from Dr. Donna Green, an associate professor at the University of New South Wales, Australia and a founding member of the Climate Change Research Centre, “[Intellipure] uses a different process, which may meet or exceed the filtration standards of a HEPA, but that only makes it HEPA like, not true HEPA.”
The HEPA filter level of efficiency is set by the United States Department of Energy, but manufacturers do not receive certification for their filters from the government. Dr. Martin said, “HEPA filters are tested and certified by their manufacturers according to consensus standards.” The consensus testing standards he referenced come from the Institute of Environmental Sciences and Technology, a nonprofit membership organization.
