What is formaldehyde cancer risk?
Formaldehyde causes more cancer than any other toxic air pollutant. It is emitted from cars, trucks, planes, industrial facilities and many other sources. It’s also formed in the atmosphere when other chemicals are cooked by sunlight. However, the risk we show you is an underestimate in two ways: First, it does not include the risk from inside homes or workplaces, which studies show to be much higher. Indoor formaldehyde comes from things like gas stoves and certain kinds of furniture. Second, the EPA estimate does not include the risk of myeloid leukemia, the most common cancer caused by the chemical. The EPA calculated that risk but said it did not have enough confidence to include it in its overall assessment. If it were included, the cancer risk from formaldehyde in outdoor air would be shown as about four times higher. Read more →
Compared with the rest of the U.S.
Most of the U.S. has a cancer risk from formaldehyde of higher than 1 in 100,000. Here’s how your block compares.
Compared with other air toxics
Formaldehyde is just one of dozens of toxic chemicals that contribute to outdoor cancer risk. Usually formaldehyde is the biggest source of your outdoor risk, but in certain industrial areas, other chemicals may have higher risks.
Where does outdoor formaldehyde come from on your block?
The EPA's AirToxScreen database is a model that predicts how different sources combine in your census block. These sources fall into broad categories.
What is secondary formation of formaldehyde?
In most places around the country, the majority of your outdoor cancer risk from formaldehyde comes from a chemical reaction in the atmosphere and can’t be easily traced to individual sources.
The amount of what’s called “secondary formation” of formaldehyde on your block depends on many variables, from the number of cars, trucks, airplanes and refineries to climate, geography, and even what kinds of soil and vegetation you have in your area. Certain trees produce a chemical called isoprene that reacts with heat and nitrogen oxides in car and truck traffic to create formaldehyde. This is one reason secondary formaldehyde levels are higher in the south. But these trees serve as an amplifying force in already dirty air, Joost de Gouw, a professor at the University of Colorado, told us.
If, hypothetically, there were no cars or industrial emissions, the levels of formaldehyde would probably lower by “a factor of three, four or five,” de Gouw said.
That means the amount of emissions that can be released into the air before a dangerous level is reached varies widely around the country. In places like Atlanta, surrounded by forests, more stringent regulation of nitrogen oxides might be needed to lower risk, according to de Gouw.