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You don’t buy An air purifier in a vacuum, literally. Maybe your old purifier doesn’t work anymore or you’re a newbie to indoor air, but it’s time for you to buy an air purifier.
While you may be tempted to buy something small that can be stored under a desk or that viral purifier that keeps popping up on your FYP, I suggest you rethink the very act of buying an air purifier. And, while in your research you may read about aesthetics or how the purifier blows air out, such as from below or horizontally, None of that matters If the purifier is too small to clean the room or is placed in the wrong location, such as on a windowsill or against a wall.
For more tips on keeping your indoor air quality in check, check out our guides to the best air purifiers and the best indoor air quality monitors.
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Step 1: You’re not buying an air purifier, you’re… Adapting your room for an air purifier
Photography: Lisa Wood Shapiro
Before you browse online or head to the store, think about the process of buying an air purifier as How to equip your room with an air purifierWhile we don’t use the word “horsepower” in terms of air purifiers, when matching them to your room, you’re actually looking at air exchange power.
The main question: Is that cute viral air purifier powerful enough to clean the air in your bedroom or living room? And how can you figure that out? The first part is doing some third-grade math. You’ll need a tape measure. I used a basic 25-foot tape measure I bought at a hardware store years ago. With the help of one of my kids, I measured the length of the room and then the width, and then multiplied the length by the width to get the area, or square footage.
Step 2: Ceiling height is important
Even though you’ve found the area of your room using the length times width formula, you’re not done yet. And before we go any further, the height standard used in many air purifier calculations, known as the clean air delivery rate, or CAD—is an 8-foot-high ceiling. When you add up the height by multiplying the length times the width times the height, you get the room volume, or cubic square feet. Sometimes, depending on the air purifier model, you’ll need the cubic square feet; sometimes, you’ll need just the square feet.
Yes, sizing an air purifier in the US is confusing due to American measurement systems; Nate Bargatze explains it well in this sketch from Saturday Night LiveI digress. Back to your room: Rooms with high ceilings, such as vaulted ceilings, cathedral ceilings, double-height ceilings, and the like, will have the added burden of calculating the cubic square footage of the room, because this will mean you’ll need a larger air purifier or two purifiers to clean the air.
Step 3: It’s all about numbers
Photography: Coway
The most important room is the one you spend the most time in. For most people, that’s the bedroom. Let’s say you’ve found the size of your bedroom and it’s 200 square feet, and the ceiling height is around 8 feet. You find an air purifier with an advertised CADR of four air changes per hour for 200 square feet. That’s not going to be loud enough. Why? Most air purifiers are loudest on their highest setting, like 50 decibels or more, similar to a modern refrigerator. That means when you run that same air purifier on a lower setting, it’s not going to efficiently clean the air in that 200-square-foot room.