A new study has revealed that using a home air purifier with a HEPA filter for just one month may improve some brain functions in adults over 40.
HEPA air purifiers, short for "high-efficiency particulate air," are used to remove fine particulate matter from the air inside homes. These particles, often resulting from car exhaust and traffic pollution, are linked to an increased risk of respiratory and cardiovascular diseases, as well as neurological conditions such as Alzheimer's and Parkinson's.
Although environmental health experts are increasingly recommending the use of these devices to reduce exposure to air pollution, studies investigating their direct impact on mental abilities remain limited, especially among people living near highways and areas with heavy traffic.
The study was based on an analysis of data from 119 people aged between 30 and 74, living in Somerville, Massachusetts, an area known for high levels of air pollution due to its location along Interstate 93 and Highway 28, both major busy roads.
The researchers randomly divided the participants into two groups. The first group used a real air purifier with a HEPA filter for one month, then used a dummy device for another month—a device similar in appearance and function but without an air purifier—with a rest period between the two phases. The second group used the two devices in reverse order.
After each stage, participants underwent tests to measure a number of mental functions, such as visual memory, motor speed, executive functions, and mental flexibility, which are skills related to concentration, organizing thoughts, speed of response, and decision-making.
The results showed that participants aged 40 and over, who made up about 42% of the study sample, were able to complete the mental flexibility and executive functions test 12% faster after using an air purifier with a HEPA filter, compared to using a placebo.
The researchers confirmed that this improvement remained even after accounting for other factors that could affect the results, such as the length of time participants stayed indoors or the level of stress they felt during the tests.
Although the improvement appears to be limited, the researchers explained that it is roughly equivalent to the cognitive benefits resulting from increased daily physical activity, noting that preventing cognitive decline—even if slight—is very important in the long term, because any small decline in mental performance may be associated with an increased risk of serious health problems, and even a higher risk of death.
Researchers point out that people who live near highways or main streets are exposed to higher levels of air pollution and have higher rates of related diseases.
There are still questions that have not been resolved, including whether the benefits will be greater for older people, especially since the number of participants over the age of sixty in the study was very limited, as well as whether using air purifiers for longer periods will lead to better and more sustainable results.
Researchers are also seeking to understand how these devices affect the brain, as previous studies indicate that microparticles may negatively affect the brain's "white matter," which is responsible for transmitting nerve signals and maintaining communication between different brain regions.
The research team plans to continue studying this relationship to see if reducing fine particles inside homes can actually protect the brain and help reduce cognitive decline associated with air pollution.
The study was published in the journal Scientific Reports.
