Amid all the noise about chemicals in the home, these are three scientific, data-backed ways to reduce formaldehyde in the home. Once you’ve understood how to assess formaldehyde in your home and why testing machines are unreliable, here’s how you can act to reduce formaldehyde.
Method 1: Open a window, since outdoor air has virtually no formaldehyde.
Even in developed urban areas, outdoor concentrations of formaldehyde are near zero.
The only problem is, opening the window in a polluted city will bring in polluted outdoor air. The sky outside our windows isn’t always this blue.
Sometimes the world outside my Beijing window looks like this.
If you have a central air system that brings in outdoor air and filters it, you’re good! But if you don’t have that, it’s not cheap to install, so you’re left with method 2…
Method 2：Use activated carbon filters.
Because we’re an open-data start up, Smart Air tested this question by ordering formaldehyde straight from the factory in China (for science!).
Formaldehyde solution—straight from the factory!
Results showed that the carbon filters effectively lowered formaldehyde levels and other VOCs.
With a fan only (red line), formaldehyde levels stayed high. But with a carbon filter on the fan (blue line), formaldehyde levels went down.
But you don’t need to believe me. All the data and methods are open source:can carbon remove formaldehyde?
But pay attention for how much activated carbon is in your filter. Lots of purifier companies say their purifiers have carbon, but their filters only have a slight dusting of carbon, such as the Coway filter below. If you can’t see the tiny black dots of carbon, your eyes are normal!
Don’t even bother with these “carbon bags” popular in China. Because there’s no fan, hardly any air passes over the carbon, so they likely have close to no effect (tests of plants in real-world homes—as opposed to tests in tiny sealed containers—have also found no detectable effect on formaldehyde).
Method 3: Try a formaldehyde home cookout!
Since formaldehyde off-gases faster when temperatures are high, you might try throwing a home cookout. Set your heat to high, turn on a humidifier, and get the heck out!
However, I call this method “not so serious” because I’ve never seen anyone actually test it. One thing I’m sure of is that I would not say is that this will completely solve your formaldehyde problem. The best case scenario is that this would off-gas a portion more formaldehyde than normal.
3 Things You Need to Know About Formaldehyde
Thomas is an Associate Professor of Behavior Science at the University of Chicago Booth School of Business and the founder of, a social enterprise to help people in China breathe clean air without shelling out thousands of dollars for expensive purifiers.