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- Hi my name is Tim Heffernan, and I'm a senior writer
at Wirecutter, where I've spent the last four years
testing air purifiers.
The kind of purifier we're talking about here today
is called a HEPA purifier.
That stands for High Efficiency Particulate Air,
or High Efficiency Particle Arrestance.
They are fundamentally simple machines.
They consist of a fan, and then a dense filter,
and when air is drawn through that filter by the fan,
virtually all the particles in the air are rapidly captured.
However, air purifiers can't purify everything.
And so we're just gonna go through today
the things that they can do, the things they can't do
and stuff that you can do to maybe
address those other things.
(jazzy music)
All right.
Smog, this is a yes, but.
Smog is a really complex mix of substances.
Certainly it contains a lot of soot and other particles.
A HEPA filter is very, very good at getting those
out of the air.
But smog also contains a lot of volatile organic compounds,
essentially, chemicals that have been evaporated
into the air, and a HEPA purifier is not good
at removing those.
Essentially, those molecules are too small
to be captured physically by the filter,
to really make a meaningful difference.
Pollen, this is a clear yes.
Pollen grains are typically around 10 microns in size,
or larger.
HEPA filters easily capture particles of that size.
They are tested on particles of 0.3 microns,
so 30 times smaller.
And they really have no trouble at all.
The one thing is, the pollen will settle on surfaces.
If you really want to get rid of all of it,
you'll need to mop or dust, or ideally do both
of those things.
Dust, this is also a yes.
Dust, like pollen, tends to be of such a large particle size
that HEPA filters are easily able to capture it.
The same caveat applies, though,
dust will also settle on surfaces.
If it's there, it's not going through the air purifier
so you'll need to get rid of it by mopping and dusting.
Paint fumes, this is a no.
HEPA purifiers, again, are really designed just to remove
particles from the air.
And when you're talking about volatile organic compounds,
odors, those are molecules that have evaporated
into the air.
They're too small for the physical filter
in a HEPA purifier to capture them.
Wildfire smoke, this is a real yes, but.
The answer for the smoke particles is absolutely yes.
Smoke particles fall right in the range
that HEPA purifiers remove very efficiently,
and so they can do a really, really good job
of getting smoke out of your home.
This said, wildfire smoke also does contain
volatile organic compounds,
chemicals that are coming from burning trees,
burning wood, burning road surfaces,
and HEPA purifiers are not very good
at getting those out of the air.
Between the choice of having a HEPA purifier
and not having one during a wildfire smoke,
it will make a huge difference in your quality of life.
Marijuana smoke and cigarette smoke.
Also yes, but.
Again, smoke particles, right in the size of particle
that HEPA filters are excellent at getting out of the air.
Course, both of these things do produce odors, VOCs,
which purifiers, HEPA purifiers are not great at.
And also, the smoke gets into furniture,
gets into carpets and so any time you move around,
you're gonna be kicking up more of those particles,
and you may well breathe them in
before they get into your purifier.
Ah, viruses, this is another no.
Viruses are generally too small to be captured
by HEPA filters.
A lot of purifiers do contain a UV bulb
that's designed anyway to kill pathogens
that are in your air.
We are unable to test for that,
but if it's something you're concerned about,
it is an option.
So this is our drawing of pet odors, this is a no.
Again, similar to other things,
odors are basically small molecules
that are floating around in your air,
and they're too small for a HEPA filter to get rid of 'em.
Pet hair and pet dander in general, that is a yes, but,
as many of these are.
Any pet hair and pet dander that's floating around
in your air,
a HEPA purifier will very easily remove that.
I mean, relatively speaking, those things are huge particles
and these'll have no trouble at getting them out.
The thing is, a lot of pet hair and dander
is simply too big to float around in the air
for very long in the first place.
So again, it's a situation where your best bet
is not an air purifier, it's just regularly vacuuming,
mopping, sweeping.
Mold, this is a yes.
Mold spores are generally much larger
than the 0.3 micron minimum that HEPA filters are tested at.
They are small enough to be floating around
in your air, however, and a HEPA purifier
does an excellent job of removing them.
If you're thinking about getting an air purifier,
first think about the specific problem
you're trying to address.
I think the main takeaway is that you can see that
yes, and yes, but really kind of dominate,
but if you have a problem with volatile organic compounds,
with odors, that's when you need to look for
a machine that can do a bit more.
How many air purifiers do I use?
I've three going in my house right now.
Earlier this year, I shut one of them off for a few days.
In fact, the next three or for days
I'm just sneezing and sneezing and really had no idea why.
I'd become so used to having purified air in my home.
So yeah, they seem to make a difference.
- [Nikki] I would love that.
- I warn you, I played frisbee.
- Really? - Yeah.
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