Using a HEPA purifier at home for one month stimulates a small but significant improvement in brain function in adults age 40 and older. That is the result of a new study we co-authored in the diary Scientific Reports.
HEPA Purifiers – HEPA stands for High Efficiency Particulate Air – remove particles from the air. Exposure to suspended particles has been linked to respiratory and cardiovascular diseases as well as neurological diseases such as Alzheimer’s and Parkinson’s. Environmental health researchers increasingly recommend that people use HEPA air purifiers in their homes to reduce your exposure to particlesbut few studies have examined whether its use improves mental function.
We analyzed data from a study of 119 people ages 30 to 74 who lived in Somerville, Massachusetts. Somerville is located along Interstate 93 and Route 28, two major highways, resulting in a relatively High levels of traffic-related air pollution.. This makes it an especially good place to test the health effects of air purifiers.
We randomly assigned participants to one of two groups. One used a HEPA air purifier for a month and then a fake air purifier (that looked and acted like a real one but did not contain the air cleaning filter) for a month, with a month’s break in between. The second group used the real and fake purifiers in reverse order.
After each month, the participants took a test that They measured different aspects of their mental capacity. The test probed people’s visual memory and motor speed skills by measuring how quickly they could draw lines between sequential numbers, and assessed executive function and mental flexibility by asking them to draw lines between alternating sequential letters and numbers.
We found that participants ages 40 and older (about 42% of our sample) completed the mental flexibility and executive function testing section on average 12% faster after using the HEPA purifier than after using the sham purifier. This was true even when we took into account factors such as differences in the amount of time participants spent indoors, with either filter, as well as how stressful they found the test.
This improvement may seem small, but it is similar to the cognitive benefits that people experience when increasing your daily exercise. While you may not experience a sudden increase in clarity with a 12% increase, preventing cognitive decline is vital for long-term well-being. Even small decreases in cognitive functioning can be associated with increased risk of death.
Why is it important
Air pollution can negatively affect mental function after a few hours of exposure. Studies show that air purifiers are effective in reducing particlesBut it is unclear whether these reductions can prevent cognitive damage caused by ongoing pollution sources such as traffic. There has been a particular lack of research in people who live near major sources of air pollution, such as roads.
People who live near highways or main roads. are exposed to more air pollution and also experience higher rates of air pollution-related illnesses. These risks are not faced by all Americans equally: people of color and low-income people are more likely to suffer live near highways or areas with a lot of traffic.
Our study shows that HEPA air purifiers can offer significant health benefits in these circumstances.
What is not yet known
Research shows that air pollution is beginning to affect cognitive function especially strongly around 40 years old. These effects may become increasingly prominent as people age.
Therefore, HEPA air purifiers may be especially beneficial for older adults. Our study did not explore this possibility, as fewer than 10 of our 119 participants were over 60 years of age.
Additionally, our participants only used a HEPA air purifier for one month. It is possible that a longer duration of air purification could maintain or even increase the improvement in cognitive function that we observed in our study.
Lastly, it’s unclear exactly how air purifiers improve cognition. Some studies suggest that exposure to particulate matter Reduces the amount of white matter in the brain.that helps brain cells drive electrical signals and maintains connections between brain regions. The brain regions most affected by air pollution are those that control mental flexibility and executive functionthe same domains in which we saw improvements in our study.
We plan to study whether reducing particulate matter through the use of air purifiers actually protects the white matter of the brain and whether it could reverse some cognitive decline. We’ll explore that possibility by studying how levels of molecules called metabolites, which cells produce as they do their work, change in response to breathing polluted air and air cleaned by a HEPA filter.