When we think about harms of air pollution, we often think about the health impacts on infants and the elderly. But does air pollution affect the health of young, healthy people? And if so, can air purifiers help reduce the health impacts of air pollution?

Do purifiers have real health benefits?

Researchers gave 35 college students in Shanghai real or fake purifiers and tracked several health markers for two days. Researchers tested the students’ lung function and several health markers in their blood.

First, reality check: did the purifiers reduce the number of particles in the air? The red line here is outdoor PM2.5. The blue line is indoor PM2.5 for students using the fake purifier.

Not surprisingly, fake purifiers don’t work. And note that these are bad levels of pollution. The World Health Organization’s annual limit is 10 micrograms. Without purifiers, these rooms were averaging 100 micrograms!

But check out PM2.5 levels in rooms with real purifiers (yellow).

PM2.5 levels were about half as high in rooms real purifiers.

But we already know purifiers reduce pollution. Did the purifier actually have effects on their bodies? Here’s what having a real purifier did to measures of inflammation:

The students had significantly lower inflammation. They also had fewer markers of blood clotting (coagulation):

And they had less constricted blood veins:

One of the only things that did not improve significantly was their lung function:

Three Things I Didn’t Know Before This Study

1. The real harm of pollution isn’t in our lungs

My intuition with air pollution has always been that the biggest worry is lung problems like asthma and lung cancer. Air pollution does affect our lungs, but epidemiological studies are finding that effects on our lungs are far smaller than effects on our hearts and blood vessels. Air pollution kills about three times as many people through heart attacks and strokes than it does through lung cancer and other lung problems. 

2. Health effects are real even for young, healthy college students

Remember that these aren’t old people. And they’re not people who joined the study because they already had problems. They’re young, healthy people. These results suggest that air pollution is taking a toll on our bodies, even if we are still mostly healthy.

3. The benefits were detectable within 48 hours

These students’ biomarkers of inflammation changed in just two days. Air pollution has long-term effects like cancer, but it also has short-term effects like inflammation and blood pressure (which probably help cause those long-term problems). And because these results are compared to people who received a fake purifier, they cannot be explained by a placebo effect.

But this is only one study…

Like any finding, we should be wary of making conclusions based on a single study, but there are at least four other recent studies out with similar findings (1, 2, 3, 4).