HEPA Air Purifiers May Enhance Cognitive Function After Just One Month: Study
Using a HEPA air purifier at home for one month was linked to a small but significant improvement in brain function among adults aged 40 and older, according to a study published in Scientific Reports.
Researchers analyzed 119 adults aged 30 to 74 living in an area with relatively high traffic-related air pollution. Participants were randomly assigned to use either a real HEPA purifier or a sham purifier for one month, followed by the other device after a month-long break.
After each period, participants completed cognitive tests assessing visual memory, motor speed, executive function, and mental flexibility.
Among participants aged 40 and older, those who used the HEPA purifier completed the test measuring executive function and mental flexibility 12% faster than after using the sham purifier. The association remained after researchers accounted for factors including time spent indoors and test-related stress.
HEPA filters are designed to remove particulate matter from indoor air. Long-term exposure to particulate air pollution has been associated with respiratory and cardiovascular diseases, as well as neurological conditions including Alzheimer’s and Parkinson’s disease.
Researchers suggest that reducing particulate exposure could benefit brain function, particularly because cognitive effects of air pollution may become more pronounced from around age 40. However, the study does not prove that air purification prevents cognitive decline.
The findings also have important limitations. Participants used the purifier for only one month, and fewer than 10 participants were over age 60, meaning the results cannot yet be generalized to older adults. Researchers also do not know exactly how cleaner air may improve cognition.
Future studies will investigate whether longer-term air purification can produce sustained cognitive benefits and whether reducing particulate exposure may protect the brain’s white matter.
REFERENCE: Nicholas Pellegrino, Misha Eliasziw, et al.; Effect of HEPA filtration air purifiers on cognitive function from a secondary outcome analysis of a pragmatic randomized crossover trial. Scientific Reports, 2026; 16 (1) DOI: 10.1038/s41598-026-48063-8
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