“Where should I place my air purifier?” is a common question people have when getting an air purifier. Does an air purifier’s position affect its performance? Is it best to put an air purifier next to a wall? Is it better to put it close to me? This post provides a data-backed answer on how to best place your air purifier in your living room, classroom, or office space.
1. Best Place to Put an Air Purifier: Distance From Wall
For purifiers to work best, they need enough space to draw in and circulate air throughout the room. If it’s backed up against the wall, it can’t take in as much air and limit its airflow.
So how far from the wall should the purifier be? I decided to put Smart Air purifiers to the test. Here’s how:
I ran the test on three Smart Air purifiers. The Blast, Blast Mini, and Cannon. Here’s the data averaged out over the 3 air purifiers:
When the purifier was flat against the wall, the airflow was only about 5%! Moving the air purifier 4 cm from the wall increased the airflow from 5% to 94%. At 10 cm from the wall, airflow was back up to 100% of its normal value. But if you want to be conservative, 15 cm would give a stronger guarantee that you’re getting the most airflow.
Keep Your Purifier a Hand’s Length from the Wall
Since not all air purifiers have exactly the same inlet, a safe bet would be to keep your air purifier inlet at least 15 cm from the wall. 15cm (or just under 6 inches). This distance is roughly the length of an adult hand. Use your hand to make sure your purifier is best placed away from a wall.
Is it better to sleep next to your air purifier? Does the location of the air purifier in your room matter? To find out, Smart Air did seven overnight tests to see if the air closer to the air purifier is cleaner than other spots in the room.
2. Best Place for an Air Purifier: Location in Room
Does the location of an air purifier in a room matter? Is it better to place the purifier in a location closer to you? We often get asked by schools, “Where should an air purifier be placed in a classroom?”
To find out, the Smart Air team placed three Dylos DC1700 pollution particle counters in different spots (and heights) in a room. Then a Smart Air DIY Cannon air purifier was turned on at night, and particle counters tracked the pollution levels throughout the night. The particle counters took turns in each location over the course of multiple nights to account for any variations that might exist between the counters.
In the 15 m2 room, the table was closest to the air purifier, while the sofa was the furthest. Would the location closest to the air purifier have the cleanest air? If so, this could confirm that it is best to put an air purifier as close to you as possible.
It turns out the differences between locations were TINY. Here’s how much effectiveness deviated from the overall average across the locations:
You can see how similar the decreases were in this sample test on one particular day. Although there’s a little bit of difference at the beginning, the three lines track each other closely.
The table, which was closest to the air purifier, had only slightly better air quality compared to the other locations.
If we look at the percentage reductions in particles, the differences between locations were less than 1%.
Smart Air ran the tests in a 15m2 bedroom with the doors and windows closed. The DIY Cannon air purifier was strong enough for the size of the room. Finding the right air purifier with enough power (CADR) for your room size is more important than the position of the purifier. In addition, if you sleep with the air purifier on low, make sure the low setting CADR is enough for your room size.
Open Data
As always, I’m making the data and more info on the test methods openly available for all you fellow clean-air nerds. You can download the test data here.
P.S. What About Big Spaces?
Of course, results might be different in big rooms, like a big open office. If you want to see results for a bigger area, check out this test I ran with a single purifier cleaning an entire Beijing apartment.
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Dyson claims that CADR is a useless metric because without any external mixing or a super efficient outflow of air from the purifier, an air purifier is effectively just purifying the air in its close proximity ONLY over and over again. I do find a flaw in their reasoning – if a purifier is indeed pushing out air at higher CADR it has to push it hard and thus propel air further. BUT having said that, how would the presence or absence of a ceiling fan affect the air quality in a room? Have any tests been done on this?… Read more »
This web site and its company, are great. However, I am confused mostly with the size that I need. Two story home, 2800sf. Three bedrooms upstairs with open balcony at the top. Somehow I don’t think two of us need the BLAST! Does that mean I should get two purifiers, one for each floor? Upper floor is much smaller than lower. We live in the country in Western New York and get a LOT of tree pollen. We pretty much live in the woods. We are also going to get smoke from Canadian fires again. Suggestions on this issue is… Read more »
The transmission of Covid in schools has now become a real concern – particularly with the advent of more transmissible versions, and a growing appreciation of health impacts such as long Covid. Warm, moist airborne exhalation may result in droplets falling down in a matter of minutes, but are a concern when many are in close proximity. One solution may be a 360 degree intake air purifier (such as the Sqair) surrounded by a circle of students. With localised air purification, perhaps multiple surround intake air purifiers – each having its own circle of people? What is the opinion of… Read more »
In Australia the inexpensive IKEA CADR 140 VERTICAL FILTER air purifier actually takes in air from the front – unlike the three Smart Air purifiers mentioned, where intake is at the back.
My modest Ikea air purifier is placed on the floor – with output, at a right angle, directed upward.
However, in view of this frontal intake the unit can actually be attached to a wall – 90 degree rotation allowing output to also be directed to either side, only downward exhaust being precluded by Ikea.
thx for this article!!! now i know more about air purifiers… i almost got scammed by a company claiming their purifiers are superior since it purifies the air on the ground (unlike most tower air purifiers) for babies and kids!! now i know it was all marketing gimmick😡😡😡 they claimed in the product description that most other purifiers cant clean the air on the ground!!! a lie!!!! 😡😡😡😡