Many Schools Are Buying High-Tech Air Purifiers. Do They Actually Work?

13:56 minutes

white woman sitting on steps outside of house, looking pensive
Melanie Robbins, mom of a kindergartner and a child in pre-k in Montclair, New Jersey, joined a campaign of concerned parents who tried to raise concerns with the Montclair Board of Education over the use of Global Plasma Solutions ionizing devices in their children’s public school classrooms. Credit: Jackie Molloy for KHN

an orange button that has two logos, one in white that reads "scifri" and a blue square with white font that reads "khn"This story is a collaboration between Science Friday and KHN. Read the story by KHN’s Lauren Weber and Christina Jewett.

As students head back to school, parents are getting a lot of mail about what schools are doing to better protect kids in the classroom—from mask policies to spacing to lunch plans. One item on many administrators’ lists of protective measures is improving classrooms’ ventilation. 

Many studies have shown that better ventilation and air circulation can greatly reduce COVID-19 transmission. But rather than stocking up on HEPA filters, some districts are turning to high-tech air purification schemes, including untested electronic approaches and airborne chemicals.

Christina Jewett, a senior correspondent for Kaiser Health News, has written extensively about school air filtration and purification. She joins Ira to explain why some air quality experts are less than convinced by the marketing claims made by many electronic air purifier companies. 

Further Reading

Segment Guests

Christina Jewett

Christina Jewett is a senior correspondent with Kaiser Health News in Sacramento, California.

Segment Transcript

IRA FLATOW: This is Science Friday. I’m Ira Flatow. As students head back to school parents are getting a lot of mail about what schools are doing to better protect kids in the classroom, like mask policies, spacing, lunch plans, and more. And one item on many lists is improving ventilation. Of course, better ventilation and air circulation can be key to fighting the COVID virus, but it turns out that some districts are turning to high tech air purification schemes that may be more hot air than clean air and could even be harmful.

Joining me now is Christina Jewett. She’s senior correspondent for Kaiser Health News based in California. She’s written extensively about this. Welcome to Science Friday.

CHRISTINA JEWETT: Thank you, Ira. Glad to be here.

IRA FLATOW: As I say, you have written several articles about this idea of air purifier and ventilation technology. What got you interested in this?

CHRISTINA JEWETT: Well, you know, last November, this came to my attention, not as a journalist, but actually as a mom, I got curious about what type of air cleaning my son’s school district was going to be pursuing, and I happened to gander at the school board agenda, and I saw that they, apparently, found something that was going to be better and cheaper than a Hepa filter. And I’ve been covering health care workers dying of coronavirus last year, and I had a lot of time logged talking to hospital’s occupational health and safety experts, about how to keep workers safe. And I was stunned that there was something better than the Hepa filter.

So I thought, well, I need to dig deeper into this. It’s time to do some research. And what I discovered was that there are a lot of indoor air quality experts who are actually very skeptical of a lot of claims that are made by folks in this air purifier industry.

IRA FLATOW: Can you give me an idea what technology they are offering that people are saying, I’m very skeptical about?

CHRISTINA JEWETT: So on one side you’ve got the Hepa filter, basic mechanical, easy to imagine. You’ve got a fan. You’ve got a filter that traps things. Simple, right? But then there’s this whole other universe of, what they call, electronic air cleaners. And they do a lot of different things. They take an electrical charge, and they change molecules in the air. They’re called ionization, bipolar ionization, photo catalytic oxidation. Some use what they call reactive oxygen, or dry hydrogen peroxide.

There’s actually quite a variety out there. The notion is that they’re taking the coronavirus and, basically, zapping it. And the experts I’ve talked to are really concerned about these claims because, if these devices are powerful enough to have that effect, then the likelihood is that there’s a lot of other gases in the air that are getting turned into something else, as well. And that’s an area where there’s just a real lack of study and evidence of what your kids marker fumes or the gas from the cars idling outside or the Axe body spray is going to turn into when it hits one of these reactors.

So there is a lot of concern about the unintended effects of these devices. And then there’s also some concern about whether some do much of anything at all.

IRA FLATOW: What do you mean, do much of anything at all?

CHRISTINA JEWETT: Well, for instance, the companies that make these devices do a lot of studies. It can be hard to get your hands on the studies, but when you do, sometimes what you see is that the conditions in the study are not really close to resembling the conditions of how the device works in the real world. You might see something like 60,000 ions per cubic centimeter. Well, that’s going to have an effect, but how many ions per cubic centimeter does this device deliver to a classroom? That’s something that’s harder to find out and the range we’ve found has been about 2,000 to 10,000, which is a lot less than 60,000.

So when you have a study and the results ending up in the marketing pitches, with studies that are just really hard for everyday people to interpret, it’s just very difficult to understand what that’s going to do in your kid’s classroom.

IRA FLATOW: So the filtration companies might go to a school board meeting and offer their special kind of filtration and sort of snow the committee because they are not offering the kind of evidence the committee can analyze.

CHRISTINA JEWETT: Well, here’s the interesting thing there. The filtration is what you want, right? That’s the basic, old fashioned, standard Hepa technology. That’s what the CDC is recommending. That’s what the indoor air quality experts I’ve talked to say is really the most proven technology. But your Hepa filter is kind of like a hair of khaki pants or a garden hose. It’s not on patent. It’s not expensive. It’s not that hard to find. And there’s not a sales force for it.

But what you do see is the more electronic air cleaners. Those are the companies going to the school boards talking about ionization, bipolar ionization, needle point bipolar ionization, technologies that you’ve probably never heard of that sound really amazing. They sound spectacular. And some of the caution I’ve heard from indoor air quality experts is that, when they’re talking about a 99% reduction of something, you really have to look at that in context of the reductions you see with gravity and time. And gravity and time reduce things by 99% eventually. Someone with COVID sneezes, and give gravity and time a chance, and they’ll make that disappear.

So some of the studies that school boards really, we found, don’t seem to actually be reviewing carefully, really need to be looked at with a lot of skepticism because those questions aren’t always very clearly answered.

IRA FLATOW: So then, why are schools jumping on board this technology?

CHRISTINA JEWETT: From our reporting, my colleague, Lauren Weber and I, found out that these companies are bombarding school districts. The facility manager became the most popular guy in town when the CARES Act money, I mean, hundreds of millions, started flooding into schools. So you’ve got a really motivated sales force that stands to make really high margins. I mean, we saw ads on the saying that people can make 600 plus per device on some of these electronic air cleaners.

So there’s a big push to the facility manager, the facility managers advising the school board, this sounds amazing. The school board just wants to tell the parents everything is safe. And things just sort of snowball from there. And by the time this gets to the desk of someone who might start asking some tough questions, often the ink’s already dried on a contract, and parents are being told it’s totally safe for your kid to come back to school.

IRA FLATOW: Do you have any sense of how many schools might be deploying these devices?

CHRISTINA JEWETT: Well, in April, Lauren and I did some digging and we found that 2000 schools around the country had bought electronic type air cleaners. And it was amazing to see what the companies selling these say versus what the school board hears because sometimes the school officials themselves will sort of retell the story of these devices in even more glowing terms.

I imagine there’s a lawyer for some of these companies cringing somewhere saying, Oh, my goodness. We could never say that. But the principals and the school board chiefs will advance claims that these devices are sending out molecules that are actively seeking and destroying the coronavirus and zapping it at the child’s mouth. And these are things that really go beyond what even the companies will say.

IRA FLATOW: Wow. When I hear you say that some of these devices may be putting out ozone, that sounds pretty potentially dangerous to me.

CHRISTINA JEWETT: Yeah. We did find that some of these devices do put out ozone, and if you’re curious about whether a device emits ozone, there’s a really simple way to find out. It’s not always that clear from the marketing in the advertising, but you can actually try to get it shipped to California. California is the only state with– actually has laws and regulations against air purifiers emitting ozone.

So I’ve done this. I’ve tried to buy different devices because I live in Sacramento, and suddenly cannot ship to California. I say, Uh-oh. That is definitely a red flag.

But Yeah. Some of these devices, especially there’s been a lot sold in New Jersey, they emit ozone, and ozone is a gas of concern. I mean, it can damage the lungs of children. There’s research that’s shown that it mounts an immune response in the lungs. The lungs treat it as a foreign invader. And it can trigger asthma attacks, and there’s even some research suggesting that it could potentially cause asthma in kids who are otherwise healthy. So ozone is definitely not something you want to be introducing into a classroom.

IRA FLATOW: One of the other approaches I’ve seen mentioned is powerful ultraviolet lights in air ducts or filter boxes. I mean, we know that UV light can kill germs. Is there good evidence for that technology working here?

CHRISTINA JEWETT: That has more evidence. So the upper room germicidal UV has a pretty good research base behind it. One of the things the experts I’ve talked to have mentioned is that you don’t want a child’s eye on the UV. It can actually damage the eyes. I was touring preschools for my younger son, and one of them said, Oh, we have a UV wand, and we disinfect the toys every day. And I said, in front of the kids? And, No, no, just the staff. I said, OK. Do they have eye protection? No. OK.

So as we go into the sanitizing state of mind, we really have to keep doing that research to make sure everything is being done in the safest possible way.

IRA FLATOW: Is there any kind of regulation or certification these devices have to go through? Does anybody review them?

CHRISTINA JEWETT: You know, that’s a really good question, and it’s a question we asked a lot of government agencies. And I wanted to start with the FDA. I thought, well, we’ve got to do something about this. But basically, they don’t do much about it if you’re not making a disinfecting claim about something going on inside the body. Since it’s outside the body, that goes to the EPA. And they have regulations on pesticides, and I learned that bleach is a pesticide. Like anything that the claims to kill a pest, which could be a bacteria or virus, like these devices, is considered a pesticide device.

And so the EPA regulations are so old that, where you might have a requirement to test something you spray or a liquid like bleach to see how effective and safe it is, those regs don’t actually apply to these disinfecting air purifiers. So basically, there’s really no government agency that’s looking at any kind of apples to apples. You know, is this safe? Is this effective, evaluation that just really doesn’t exist right now.

IRA FLATOW: This is Science Friday from WNYC Studios.

So what I hear you saying is that your research shows that, Yes, everybody agrees that the cleaner air is good. You’re not arguing against schools taking steps to filter out or purify the air in classrooms. But your research is showing that just some of the simplest techniques, like the Hepa filters, the cheapest, might be the best way to go.

CHRISTINA JEWETT: You know, that’s what the experts we’ve been talking to have been saying all along. And when we started this reporting there was very little clear-throated and loud guidance from any agencies, but in the months that have passed, the CDC has come out and said, you want the portable Hepa filter. You want to look at your HVAC system and make sure you have a really good filter, like a Merv 13 filter. You want to pay attention to the air exchanges. Make sure you’ve got five or six an hour in room. And that is a really robust layer of safety.

And the CDC even just recently came out with a report showing that you have people with masks on and you’ve got Hepa filters in the room, that actually reduced the infectious aerosols from a mannequin, there was a study, of course, by 90% in a pretty quick manner.


CHRISTINA JEWETT: So there is really good research, and there’s really good direction out there now. But as far as some of these other technologies, the experts really considered the jury to be out. And we even found a study where Boeing decided to say, hey, should we use this stuff in our airplanes? And at the end of the day Boeing tested some electronic air cleaners in their airplanes and in labs and their conclusion was no. This is not ready for prime time. There’s promise to this technology, but we’re not putting this in our airplanes.

IRA FLATOW: Well, Christina, I’m happy to have you on to debunk a lot of this stuff. Thank you for taking time to be with us today. Thank you for your hard work.

CHRISTINA JEWETT: Well, happy to be here, and it’s really a pleasure, Ira. I appreciate it.

IRA FLATOW: You’re welcome. Christina Jewett, she’s a senior correspondent for Kaiser Health News based in California. She has written extensively about this subject.

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