I’ve been frequently asked whether a single purifier can effectively clean an entire apartment or house. The allure is evident – it would be more convenient, cost-effective, and less noisy to have a large purifier in the living room rather than placing one in each room.
However, the crucial question remains: can it deliver results? Can one purifier efficiently clean an entire apartment, even with bedroom doors closed? The Smart Air team undertook a comprehensive test, using an entire Beijing apartment to find out.
Test: One Purifier to Clean an Entire Apartment
I tested this in a large 134m2 (1,442ft2) Beijing apartment by putting the Blast purifier on a timer to turn on high every day from 7pm to 7am. A Laser Egg air quality monitor in each room kept track of PM2.5 continuously (how accurate is the Laser Egg?).
The Blast is a strong purifier. It puts out 890 cubic meters of clean air per hour—that’s equivalent to running three and a half BlueAir 203’s on high.
One bedroom door was always open; one was always closed. I switched which room was open and which was closed for half the tests. Windows were always closed.
Results: One Air Purifier Cleaning an Entire Apartment
Over 9 tests, the Blast reduced PM2.5 in both the room with the door open and the room with the door closed. However, the room with the door open (the Open Room) had 18% larger reductions.
That makes sense, since the purified air coming out of the air purifier could more easily enter the open room.
However, keeping the bedroom door open kept open also had its downsides. At the start of the test, the room with the door open had higher PM2.5 levels than the closed room.
In this case, the open door was letting in more dirty air from outside.
Although the room with the door open got more of the clean air from the air purifier, this room was dirtier at the start of the test. At the end of the test, both rooms had similar levels of PM2.5.
The Dirty Air Bounceback
In the two hours after the test ended, PM2.5 bounced back faster in the open room.
Open rooms have more air flow, which allows in more outdoor PM2.5. This quick bounceback is consistent with our earlier tests, which found that outdoor air pollution enters our homes constantly and quickly. That’s why I don’t recommend running the purifier for a bit, then turning it off.
12 Meters and Two Turns Away
We tested two setups. In one setup, the Blast air purifier was in the central hallway. In the other setup, the Blast was farther away in the living room:
When the Blast was in the living room, it was a long way from the two bedrooms (around 10-12m/30-35ft away). Despite the enormous distance (and two turns around the hallway!), the Blast was still able to clean both bedrooms fairly well.
As always, I’m making the data openly available for all. You can download the day-by-day statistics here (Part 1, Part 2). For the full (totally overwhelming) minute-by-minute data, email us at [email protected].
What About Larger Apartments?
These tests were in a single-floor apartment. We haven’t tested houses with multiple floors. However, if the air purifier is strong enough, it’s reasonable to guess that an air purifier downstairs would be able to help clean the air in upstairs rooms.
How I Protect Myself
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