OK, my home has formaldehyde in it. How long will it take to get back to normal?
When researching this question, I really wanted to see tests in real-world apartments. I want to understand how formaldehyde acts in real homes, not in a laboratory plexiglass container. That’s critical because sometimes people take results from sealed boxes and incorrectly apply them to our homes.
That’s critical because sometimes people take results from sealed boxes and incorrectly apply them to our homes.
For example, like I wrote an article about plants, turned out that plants had no detectable effect on particulate pollution indoors.
Fortunately, scientists in Hong Kong did real world tests. They tested for formaldehyde and other VOCs in homes and then compared new/remodeled homes with older apartments.
They found that one year after remodeling, formaldehyde levels were down 48%.
After two years, formaldehyde levels were the same as in older homes. So the data suggests it takes about two years.
But it’s worth noting that these are home in Hong Kong. Why’s that important?Because temperature and humidity make formaldehyde off gas faster. In Beijing or New York, this off-gassing will probably take longer than in Hong Kong.
Thomas is a new Assistant 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.