From The New York Times, you're listening to The Wirecutter Show.

Hey, everyone. It's The Wirecutter Show. I'm Christine Sears-Claeset.

I'm Kyra Blackwell. And I'm Rosie Garren. And we work at Wirecutter, the product recommendation site from The New York Times.

Each week, we bring you expert advice from our newsroom of 140 journalists who review everyday products that will make your life better.

This episode of The Wirecutter Show is called How to Clean the Air You Breathe.

Christine, Kyra, I got to tell you guys, I feel like this entire summer, my phone has been blowing up, specifically the weather channel app. It's not like I've been getting tons of texts, don't worry. I get these alerts that is like, The air quality, the air the air quality. Don't go outside. It's alarming, and I'm not entirely sure what to do with them.

Rosie, the first thing to do is to turn off your notifications.

But the second thing is, they just want you to click to engage.

No, but honestly, I do get what you're saying, and it's hard to know if the air is okay to breathe sometimes. If you have kids, especially, it can be concerning. I think it's really bad for people on the West Coast right now because a lot of people are in the path of wildfire smoke. Like the last few summers, the wildfire season has been really bad.

It feels like it's only going to get worse, or at least continue like this for the years to come, right?

I'm looking for some guidance on how the air, outdoors, impacts the air inside my home, and what, if anything, I can do about it. Yeah.

That's why today I'm really excited because we're going to bring in one of the country's preeminent journalists reporting on air purifiers, a wirecutter writer who knows a ridiculous amount about them and about how to keep your indoor air clean.

That's right. We're We're talking with Tim Heffernan, our senior writer who's focused on air and water quality. Tim's going to talk with us about how to determine the quality of your air, what might be making you sneeze inside, and what to do about everyday air pollution. He's also going to talk with us about what to do in emergency situations like wildfires. This is going to be a super informative episode, so you might want to take notes.

I'm ready. Got my notepad. Let's go.

We'll take a quick break and be back with Tim Heffernan, our air quality writer. See you in a sec.

Welcome back to the Wirecutter Show.

Today, we've got Tim Heffernan in the studio. Tim is Wirecutter's air and water quality reporter, and he's been testing air purifiers for nine years.

Tim, welcome to the Wirecutter Show.

Thank you very much.

Okay, Tim, before we get into asking all sorts of air quality questions, I know you go really deep on your reporting. I heard you were testing water filters. I heard you made rust water and drank it. Can you tell me? What? Can you tell me? I'm sure I'm not getting the details right.

No, you basically are.

I hoped that she wasn't getting the details right. No, good.

I was testing a filter made by LifeStraw. Lifestraw filters work differently than most in that they're like a physical blockage rather than a chemical reaction with what's in your water. In theory, they can also remove things like sediment that might be in your pipes. Being in New York, I'm used to rust in my pipes, so I thought I should test this thing on rust. An easy way to make rust, as I learned, is just take steel wool and put it into some hydrogen peroxide. It just reacts very quickly and you wind up with pure rust. I made a bunch of rusty hydrogen peroxide water. I stirred that into about two gallons of tap water and then just poured this through the filter to see if it actually worked. It sure looked like it was working. The water that was coming out was perfectly clear, but I thought, I really have to test this myself. I just drank the water, and it was great.

It was perfectly fine. There was no off weird flavor or anything? No, not at all.

It was great.

Tim is our strongest soldier at WireGuard because you could not catch me doing that. I think first we should really talk about outside air. Since it's summer and it's wildfire season. I want to know how to tell if the outside air quality is good or bad and what you can do about it. Right.

I've looked into indoor air quality monitors, which are a product that's available, but ultimately settled on recommending for most people that they just use an outdoor air quality app. The one that we recommend is EPA's AirNow. It's free. Epa maintains testing stations all over the country, so there's usually one near to you.

Tim, can you tell me for that AirNow app, there's something called AQI on that, right? What does that stand for and what does that indicate for people?

Yeah, so AQI stands for air quality index. It's just a measure of the overall quality of the air outside. And then AQI is a combined measure of a handful, I want to say it's five or six different chemicals, basically compounds that may be in the air. And it can be particulate matter and also things like nitrous oxide. But the EPA sets five levels, and they're color-coded green, yellow up to, I think, purple. That It's to indicate the general overall quality of the outdoor air. Green and yellow, that tends to be good. Maybe you want to slightly limit your activity in yellow conditions, particularly if you have pre-existing condition cardiopulmonary stuff. But as it gets higher, you should start making precautions.

When do you want to think about wearing a respirator or a mask? Is that really in the red zone, especially now that we're thinking about wildfires, if there are wildfires near where you live.

Yeah, I think once it's probably in the orange, red, purple range. That's just generally good advice. I mean, you can wear them anytime you want. Green, maybe it's not really doing much because there's not much for it to be doing, given that the air quality is good. But above that, above orange, I would say, if you can, if you could do it comfortably, you might as well obviously use a good one, like an N95 mask or something.

How does the outdoor air quality impact the indoor air quality? I mean, I can guess that it's not good and that it will seep into your home, but How is that happening and what do you need to think about?

Homes breathe. They're designed to in some ways, and certainly modern office buildings exchanging the air with the outside is very necessary. If you have bad outdoor air quality, such as wildfire smoke, It's probably your best bet to assume that your indoor air quality has gone down and then take steps to mitigate that problem.

I remember the first place I lived in New York. I didn't have an air purifier, and I lived near a major road, and the inside of my apartment often was just coated in this nasty dark grit. It was almost like sand. Nice. Right? Yeah. So gross. But I guess that's the same thing. If the outdoor air quality isn't good, then you're getting a little bit of that stuff inside your home. Also, if you live near a road, if you live near some major source of pollution, this can be an issue.

Yeah. And so things like that are going to be chronic, right? My first apartment in New York was about 20 yards from the Brooklyn Queens Expressway. I know this grit well. I remember- Shout out to Bob Moses. We would wipe the windowsill because it would get dirty and it would just smear. It was like a layer of grease, not even grit. So, yeah, that's why we basically recommend keeping an eye on what's going on outside.

Tim, does heat impact this? Because I feel like summertime, generally the air quality is worse.

Yeah. I mean, it's not simply as direct as hotter air is more polluted, but I think it's more like an overall meteorological thing. When you When you have an extended heatwave, almost by definition, you have hot air that's staying in one place for a long time. You're not getting these continuous winds that will clear out the air. The pollution that's going into the air builds up and gets worse. You can almost expect that the AQI, the Air Quality Index, is going to get worse until that heat wave breaks and a new mass of cleaner air moves in.

Okay, so what about really extreme situations like wildfires? What can you do to keep your indoor air clean when you have outdoor air that's really bad?

We would obviously recommend running an air purifier during those times, and especially run it on a higher setting than normal. Just run your air purifier on high for like an hour a day, maybe when you first get up, the hour before you go to bed. That'll do a really deep clean of your air. Then the rest of the time, a medium setting or just leaving it on auto will most likely keep your air quality actually very good indoors.

We'll talk more about air purifiers in just a second.

Yeah. I mean, other things like sealing your windows and maybe even going so far as to if it's truly smoky outside, maybe change your clothes, take off your shoes when you come in, just to reduce the amount of smoke that you're actually bringing into the home.

Do you put your clothes in a bag or something, or you can just change them and throw them somewhere?

I think some people will just designate the the area inside the front door, or maybe they come in through the garage, and you can just strip them off. You don't have to go I don't think you need to also immediately hose off. But you just... Simple, straightforward things that just limit the amount of stuff you're actually bringing into the home. If you have central air, turn it on to where it's recirculating the indoor air. You're not drawing an extra fish through the central air system.

Yeah. Tim, can I just ask, what is even in the air in the case of a wildfire? What are the particles?

Right. I mean, it's a combination of things, but the particles themselves, it's basically It's whatever has burned. So particles of carbon and other combustion byproducts that are in a physical form. It's a very fine dust-like thing. So that's the component of smoke that you can see. There's also a huge range of volatile organic compounds, basically evaporated chemicals that come from the burning. The good news is, at least according to the EPA, short-term exposure to what's in smoke like that, including these volatile organic compounds, is unlikely to have long long term health impacts. Nonetheless, again, take steps to avoid breathing it as much as you can.

What do you do if you don't have an air purifier? Like beyond just keeping the windows closed and wiping away grit?

Sure. I mean, if you have central air, you can install what are called medium nerve filters in your returns. Most return filters, if you look at them, they just look like a loose mesh of somewhat coarse string. A nerve rated filter will look more like typically white felt, but it'll be opaque to your eyes. They're just much more effective at capturing fine particles. The key, of course, is to keep your system running so that you're pulling the air through these filters continuously because it's an iterative process. Your air is cleaned multiple times.

Is this a DIY air purifier? Is Is it always like when you put the filters on either side of a fan and you run it type situation?

It's not, but those are also effective. If that's what you have, if you happen to have some filters on hand and a box fan that they will fit to, you can make these box fan filters, and they are reasonably effective. Long term, they're just large, and they're not particularly beautiful things, but they do work.

Got it.

Is there ever a time that you would want to wear a mask inside?

I guess I would say if you aren't able to take other steps or if you know your home is leaky and that outdoor air is pretty much just coming into your home, then yeah, a mask is an effective way. It's not the most comfortable thing, but it's far better than nothing.

Okay, so if I'm hearing correctly, if you are stuck in the path of wildfire smoke, the first thing you want to do is make sure your home is as sealed up as it can be.

If you have an air purifier, definitely run that. I think you had mentioned keeping things very clean and taking off smoky clothes, smoky shoes, just basically cleanliness, not tracking things inside.

Yeah, I think they're doing all those things. Basically, you've done what you can.

We're going to take a quick break, but when we come back, we'll talk about air purifiers, how Tim tests them, what he looks for, and what you can skip adding to your cart. Be right back.

Welcome back to the Wirecutter Show.

We're talking with Wirecutter staff writer, Tim Heffernan, who covers all things air quality. Before the break, we learned about how to monitor outdoor air quality and how that impacts the air inside.

Now, we're going to talk more about inside air. Tim, what are the things inside your home that might be making your inside air dirty?

You yourself are one. Humans and your pets. We shed all kinds of things, so we are actually a source. But we're talking about things like smoke from candles, smoke from your stove. If you've burned dinner, the outdoor air has a huge impact like we discussed. If it's pollen season outside, you're going to have pollen inside. Dust in general that's in the air, and you're also bringing it in when you come in from the outside, that will be in the air. A lot of it will settle on surfaces, but then you kick it up when you're walking around. Then things like certain home projects. I've been doing a lot of drywall recently. You don't have to study air purifiers to realize that you're putting a huge amount of dust in the air when you're doing that. Those are some of the common things, and they're what air purifiers are really very good at addressing.

How do you know if your indoor air is dirty to the point where it's going to affect you?

That's a really tricky question because the stuff we're talking about here is basically airborne particles, and they're so fine that you can't actually see them. You may be aware during pollen season, you'll actually be able to see that yellowish dust on things, and that's an obvious sign that this pollen is getting into your house. But a lot of times you don't know. You may have some symptoms. Your eyes may get itchy. If you have allergies, they may worsen. Those are all signs. But it's one of the tricky things about air quality is a lot of it, it can be bad, and you really don't have an indication that that's the case.

Right. It's just silent, annoying, why do I not feel super great inside my home? It could be partially due to the air quality. I know that you mentioned dust mites. That's something I had never even considered before. Then my youngest kid ended up testing positive for a severe dust mite allergy. We'll talk about air purifiers in a bit, but I have to say that I got an air purifier, and that really, really helped. Really, a lot of what you're breathing in is dust mite poop. So What we noticed with her was that her allergy, it presented as really severe eczema. I think that can also be potentially a sign that if you have some allergy, it can actually present maybe in a different way. It might not just be like a sneeze or something. It could be something that's manifesting in your skin.

Yeah, I think that's absolutely true. If you have something that seems to be chronic and there's not some other obvious cause, it's worth looking into it with an allergist or something to see if maybe that's the root cause of this issue.

While you're trying to dig into that, what tools would you suggest people utilize more, especially if they don't even have an air purifier? What can they do in their home to alleviate those symptoms?

Probably the first one is vacuuming using a dust mop. I have hard floors in my apartment and a dust mop is way faster than a vacuum for getting things like pet hair, general dust, pollen, all this stuff up and off the floor. You'll eliminate or, anyway, improve one potential source of your indoor air pollution. Slightly It's definitely more involved, but something that's worth doing anyway. If your windows are older and they're not well-sealed, you can just put the sealing strips around your windows. That'll reduce the amount of air that's coming in from the outside and keep… If it's a problem outside, it'll reduce the impact on your indoor air.

I do have a question about cleaning. It's about vacuums. Back in that old apartment, that first apartment, I had a vacuum, and it wasn't a very good vacuum. Every time I would use it, there was just dust everywhere in the air. Now I have a Miele, which has a very sealed system, so nothing gets out of it. I've noticed that that helps so much more. There's a lot less dust in my home. Is that something that you recommend, getting either a HEPA vacuum or some vacuum that has a really sealed container that it's not going to let dust out?

Yeah, no, definitely. I also have a Miele. I've never known a Xane. I don't know.

How to I always feel very self-conscious.

But yeah, they're fantastic. Again, it's true. I don't think they're necessarily true HEPA, but that has a very dense filter material used as the dust bag. I do think that people will benefit from that.

Okay, Tim. You've thrown around this term HEPA. I think that we should really just dig into it right now about air purifiers. Can you tell us more about how long you've been testing them and how exactly do they work?

Right. With HEPA filtration, just to start with, HEPA stands for high efficiency the particulate air. The high efficiency means that these are filters that let air pass through very easily. The particulate air means really that they capture all the particles that are in that air down to an extremely small scale, nanoscale particles. I've been testing purifiers for a wire cutter for about nine years now. It was actually the first guide that I picked up when I came on board. It's been a really interesting journey, if I can use that word. I think a lot of people listening will also have become more of air quality over that same nine-year span. Really beginning in 2017 or 2018, when the wildfires out West suddenly got much more extreme. Then, of course, with the COVID pandemic, indoor air quality suddenly became of paramount importance to people. And air purifiers, these HEPA air purifiers that I've been reporting on, are extremely good at addressing things like smoke and airborne pathogens.

So how did you even come up with your testing method?

The test method is actually one that replicates the standard that's used to certify a filter as HEPA. So I use the smoke from matches. If you burn a match or two, you'll actually produce millions and millions of very, very fine particles that are right around this 0.3 micron standard that's used for HEPA certification. And it's used because that's the most difficult size of particle to capture. So if the filter captures smoke very well, it's going to capture everything else, larger stuff like pollen and bacteria, all the way down to smaller stuff, including individual viruses, although they don't actually typically exist in the air as individual viruses.

Wow. Tim, can you paint me a picture here? I know you live in New York. Are you lighting matches all day long in your apartment? What's your match budget? What are we talking about here? Are you just standing next to the air purifiers? No. What's the weird.?

It sounds like you should outsource that work. That's just a match a little later.

It sounds wild. No, it's good. I no longer test at home. I did during the pandemic of necessity. But no, I burn my matches in the office so that everybody gets to enjoy this. But no, so I test in one of the offices we have there. We can seal it off reasonably well, although we've never actually really aimed to have a completely air-tight room because homes are not air-tight. We wanted something that reasonably represents real-world living conditions, and I do not stay in the room. I I earn the matches, and then I quietly exit, and I just let the purifier work and then go back in.

How long does it take an air purifier? These rooms, they're in our conference rooms, right? I don't know. What is that square footage? 200 square feet or something like that?

Yeah, about 200.

How long does it take to clear the air?

An initial load of smoke particles in there can be a million per cubic foot, and in half an hour, a decent purifier can drop that down to just a few thousand. Wow.

When I first heard about an air purifier, I thought it was like something magical. It was just the air went into this box, and then it came out clean. But actually, an air purifier is essentially just a fan with a filter, right? It's just a fan with a filter on the front, and it's sucking in air. The fan is sucking in air and pushing it through the filter, right?

Yeah. No, I mean, it's wonderfully simple, right? It's just a thing that It works. There's essentially nothing to break on it. The filters don't run out the way that something can run out of battery or run out of gasoline or something. That filter will always be working as long as the air is moving through it.

How often do you really have to change your filter then? If it never runs out. This is a dirty secret.

Should we even share it?

Yeah, sure. It's not a dirty secret. It's cool. Hepa filters actually get more efficient over time. The more air has passed through them, the more stuff they've captured, essentially because as you're adding dust and other material to the filter, you're just creating more sites for more dust and smoke to stick to it in the future. Typically, a purifier will recommend, the manufacturer will recommend changing the filter every, usually eight months or more, typically a year. You should probably do that because you can get a slight decrease in the airflow as the filter clogs up. But we've tested purifiers on filters that ran 24/7 for two years, so twice their lifespan, and there was really no measurable difference in their performance.

Every time you describe a HEPA filter, all I can imagine is like Spider-Man's web. He just keeps building more webs, the more stuff gets caught in it. I love that. That's awesome.

I have a question about in terms of, Tim, nine years go by, and presumably you're testing all kinds of different air purifiers. Is the difference between ones that are recommended on Wirecutter that you've written about versus ones you don't necessarily recommend? Is the difference one does the job and one doesn't? Or what's the nuance there?

Initially, when I started working on this category, we really, really focused on the testing most of all. But as I did this again and again, we were realizing that really any decent purifier is going to do very, very well because HEPA, again, is this very simple physical process. Over time, actually prioritizing what I call livability factors has become much more important. These things often live in a bedroom or in an office. They might be in the room where you watch TV. Things like, how much noise did they make? Most of them have LED lights on them. Can you turn them off or at least dim them so that it doesn't disturb your sleep or your TV watching? Those things have gotten much more important in my eyes, along with, obviously, really good performance. Those are things that I look at much of the time.

There's also energy efficiency, right?

Yeah. Energy efficiency is a big one. A purifier can last for a very long time, five years, 10 years. There's very little that can break on it, but they do consume energy. Energy efficiency is really a big one. Also the replacement cost of filters, upkeep cost. We look for purifiers that do a great job, they're easy to live with, and they're not going to cost you hundreds of dollars a year to keep them running.

I was going to say, I have three air purifiers, the Kowei ones that you recommend. Yesterday, I actually cleaned them. You can vacuum out. There's two filters, right? Or there's actually three filters. There's a front filter that just catches big hairballs from your cat in my home, and dust, and you can vacuum that clean. Then behind that is this black mesh. Is it carbon? Then there's the HEPA filter, which looks fancy, like folded paper, basically. We've talked about what the HEPA filter is doing, but what is the carbon, that middle carbon filter doing?

You can divide air pollution into two categories, particulate stuff, and then, broadly speaking, VOCs. These are gasses. Anything really that you can smell in the air is going to be a volatile organic compound, a VOC. Again, those are gasses, and a HEPA filter won't capture them. The black filter you're talking about, it's probably like a nylon or polypropylene mesh with activated charcoal embedded in it. Those are there to capture these VOCs, and they do do it. The problem is that unlike the HEPA filter, as the carbon filter captures stuff, it does stop working. It's sacrificial. So it doesn't last forever the way a HEPA filter does. And also there's so little of this activated charcoal in most of those filters that in terms of addressing a serious problem, you've just, I don't know, painted your walls with oil paints. You've got all these petroleum chemicals in your air. It's quickly going to become all used up and really stop doing anything.

I'm glad you told me that because I actually thought I was saving myself I have some money, and I didn't replace the activated charcoal one when I got new filters last year. I actually just put the new ones in yesterday thinking like, Oh, yes. But the old ones were probably doing nothing.

Yeah, I don't bother with them. I basically pay no attention to them.

I feel like I've seen some air purifiers that advertise different technology than HEPA filtration.

Oh, is this time for the M word?

It is time. We can talk about molecule.

Okay, so what is that?

So, molecule, it's an air purifier manufacturer. They had a very successful, very sophisticated social media campaign, and it got a lot of interest.

I got suckered, by the way. I didn't buy one, but it ended up in my cart many, many times.

I mean, MoMA had it in their shop, too. They might still. It's very chic. It's very chic. Yeah, it's a very pretty air purifier.

It is. We went through a lot of back and forth with them initially. When I approached them, they were eager to have us test it, and then they got very, very hinky about our testing, and then ultimately said, Well, you can come to our facilities, and we'll run it in front of you, and you can use that testing, which, of course, we said, No, that's not going to work. We just went out and bought their original purifier and tested it. As we discovered, it's the worst air purifier that we have ever tested.

Dings. Drama.

Essentially, what it comes down to on a mechanical level is it just doesn't move enough air. Then it has this... At that point, it on this system that they call PECO. It uses ultraviolet light interacting with titanium dioxide. That's what's in white paint. It's nothing scary. To basically chemically clean the air and neutralize and destroy particles in it. But it's not a fast process. Again, there just wasn't enough air moving through the machine.

I think it's also important to just state how expensive the molecule is. I mean, right now, depending on the model, it's between, for the small one, it's like 400, but there are some that are close to a thousand. The air purifiers we recommend on the site, the top one, the Coey, you can get that for 150, right?

Yeah. I mean, that was one of the things. When we talk about something being the worst that we've ever tested, performance per cost comes into it. On top of not working very well just on the face of it, the molecular machines back then, and to this day, are incredibly expensive relative to extremely high-performing HEPA purifiers.

So, Tim, I'm thinking back to my childhood, and I do not remember having an air purifier when I was a kid. Now, with COVID and with so many wildfires happening all the time, I feel like it's pretty common. A lot of people have them. When were air purifiers created? Is this something that just happened in the '80s or '90s, or is this a product that's been around for a long time?

In terms of an air purifier in your home, I don't know exactly when those became a thing. I know they used to sell really bad ones in the sharper image. So since the '80s, I guess.

I love the sharper image. It's so '80s, right? It is.

But HEPA filtration itself, at least in North America, apparently was born in the Manhattan Project. They were searching for a way to remove radiation from the air in the factories, and it doesn't do that. A spoiler alert. It didn't work. But they realized, Hey, we have invented this high efficiency way of removing particles from the air. In the postwar years, it saw applications in industrial settings and in medical settings. It just seems like a natural thing. Just essentially stick one of those filters on what amounts to a sealed box fan, and now you can purify the air in your home.

When it comes to having air purifiers in general, I feel like I never knew how to use mine. I feel like I put it in the wrong place. I was never vacuuming the exterior. I was turning it off to save energy and money. How are you supposed to properly use your air purifier?

In terms of placement, I don't know. You can think of it the way you might put a speaker in a room. You want it to maximize the coverage. If you can get your purifier roughly towards the middle of one of your walls, keep it a little bit away from the wall. You need that air to be able to enter it quite freely. Do not, and I've seen this happen a lot, do not put it under a table or anything like that. It's going to restrict its airflow, both coming in and maybe more importantly, going out. You want that cleaned air to be spread around the room.

When my air purifier is on high in my room, and I recognize it because it sounds like the vents that are blowing on you on an airplane. It suddenly gets really intense and really loud. I was thinking about that recently because I heard that airplanes were actually a safe place to be during COVID to a certain extent because of the HEPA filtration on planes. But how does that work? Does it work in the same way that your unit does at home?

Yeah, I mean, more or less it does. And it's true. The last I checked, and it has been a while, but this was initial post-pandemic, there was a report that said there was not a single known case of a transmission on an airplane. So airplanes, they've used HEPA filtration for years and years and years. During the pandemic, they increased the air changes per hour. Basically, they made the fan cycle the air more frequently. The little that you can turn on or off when you sit in a plane, that's blowing the filtered air onto you. So whenever I go on a plane, I just aim it right at my face, first thing.

But essentially, though, you spoke to this a little bit before, but if somebody is sick in your house, somebody has a virus, and you're trying not to spread it, will it help to put the air purifier close to that person who's sick, like a barrier?

Yeah. I mean, yes. At least in terms of, will it remove the viruses or the particles, contain a virus from the air? Yeah, it really will. It'll certainly reduce the load of viruses in the air, which is, I think, more key to transmission, how much virus is there, and then how much time are you exposed to it. If you have purifiers running, it will keep viruses and bacteria and mold spores and stuff like that at a very low level. Of course, if you're sitting right next to somebody at home and they sneeze, that's going to get on you or get to you before it gets to the purifier. In a case like that, it's not, in a sense, doing anything.

You got to just walk around holding it like your John Cusack boombox. Yes. If you really want it to be.

No. If you think too hard about this stuff, you can make yourself paranoid.

Then what do I say to my obstinate friends who refuse to heed your expert advice and don't want to get an air purifier because they, I don't know, have a lot of plants.

Plants get talked about quite a bit. I think most of this goes back to a NASA study done in the '80s, where they were looking for ways to keep the air on a space station or a Mars mission clean in a self-sustaining way. It is true that plants in general, and some species in particular, they studied a bunch, are a bit better at removing VOCs, but they do it so slowly that to keep up with just the typical ventilation in a building. Apparently, you would need to have between 10 and 1,000 plants per square meter in your home.

So that's like- Per square meter.

One per square foot on the low end. Cool.

I like my plant babies, but I can't have that many of them. That's too many plants inside. Just go live outside at that point.

Forget your kids, get plants.

But no, in seriousness, I've seen that question come up during wildfire events, and no, absolutely not. I mean, they're simply not capable of keeping up with any a critical situation.

Right. I mean, I think you can even see if you haven't dusted your plants, you can see that buildup that happens on your plants where it's just like, great.

They're not swallowing that grit. Yeah.

They're not shiny and nice.

We're asking too much of our plants. Tim, before we go, we ask all of our guests one question.

What's something that you bought recently that you really love?

I'm doing some home renovations, and I've been doing a lot of demolition, pulling down old walls and moving them. And so there were just hundreds of nails that I had to pull, and I got myself a nail puller from Nypex. I think It's the Nypex Carpenters and Cutting Pliers. But basically, they're used as nail pullers. And you can just take them, grab even just the head of a nail. If just the head is barely sticking out, you can just grab it and very easily lever that nail out. It's so fast and so much easier than with a hammer. I wanted one of these for a long time, but I was like, Do I really need this? But I suddenly did, and yeah, it was worth every penny.

This feels like it should be in a gift guide. I was going to be super sexist and say a Father's Day guide, but I in the Mother's Day guide because I also have to take nails out all the time.

Oh, yeah, it's super satisfying. It's a great wire. I really didn't mean to bring that up, but it is. It's a great wire cutter as well. You can use it for naked stuff.

All right.

You said the buzzword.

You can come back.

I love that. I love it, too. Tim, it's been great having you, and I feel like I'm going to take some of this and make my air cleaner at home.

Excellent.

Happy to help. Thanks for helping us breathe, Tim.

Thank you, Tim.

Thank you all.

Okay, that was a great conversation with Tim. I feel like I am pretty clear on what I need to do to keep the indoor air quality high. One of my biggest takeaways is that keeping things really clean is a great way to keep your indoor air quality clean. And that means obviously vacuuming and dusting. And if you're going to dust, use something damp because that will keep the dust from or the particles from just going back into the air.

Yeah. I really liked how he mentioned that you have to be mindful about how the outdoor air quality will affect your indoor air quality to the point where, yeah, you should be maybe taking off your clothes from outside as soon as you get in so you're not just bringing in the pollution. I really like that.

It makes a lot of sense. Actually, both of those go hand in hand, thinking about all the stuff that you're bringing in. Then once it's inside, you're kicking it up, and then you're breathing it in. For me, the takeaway was about the air purifiers themselves and basically how you have to keep them running I had been putting them on a few minutes here, a few minutes there, and I think I haven't been maybe maximizing their efficiency. That was really helpful.

Now that you know you can use your filter longer. You can just go to town. Just let it go. The more you know.

You feel me? That's it from us. Thanks, guys. If you want to find out more about Wirecutter's coverage on air purifiers or check out our recommended products yourself, go to nytimes. Com/wirecutter, or you can find a link in the show notes. If you like The Wirecutter show, follow us. That way you won't miss our new episodes every Wednesday.

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Either way, thank you for listening. The Wirecutter Show is executive-produced by Rosie Garren and produced by Abigail Keel. Editing by Abigail Keel. Engineering support from Maddie Messiello and nick Pitman. Today's episode was mixed by Sophia Laman. Original music by Dan Powell, Marion Lozano, Alisha Baetup, and Diane Wong. Wirecutter's Deputy Publisher and Interim General Manager is Cliff Levy. Ben Frumann is Wirecutter's editor-in-chief. Special thanks to Anil Chithrapu, Paula Schumann, Nina Lassam, Somi Hubbard, Jenn Poeyant, Jeffrey Miranda, Sam Dahlnik, Julia Bush, and Katie Quinn.

You might want to take notes. This is super informative.

Rosie?

Why are you… I'm like… Sorry.

Rosemary Rachel, you take notes. I'm not going to say it again.