Short-Term Impact of a Portable Air Cleaner on Cognitive Performance

Abstract Portable air cleaners (PACs) are commonly used to remove airborne particulate matter (PM) from indoor environments. This study evaluated the impact of a PAC on cognitive performance among 62 participants in an office environment by using a computer-based cognitive test battery of six tasks. Participants were exposed to PM from an essential oil diffuser with unscented oil and tap water during both air cleaner and placebo conditions in a balanced design. PM concentrations were 2.4 to 4 times lower when using the PAC compared to the placebo condition. Despite the significant reduction in PM levels, no significant improvement in cognitive scores was observed during PAC operation. However, using a mixed-effects model with outliers removed, a significant improvement in the feature match task was observed. When the PAC achieved a higher reduction in PM2.5 concentration, cognitive scores improved for three out of six tasks when compared to a smaller reduction in PM2.5, although the effect was not statistically significant. There was also no ordering effect between initial and subsequent placements of participants in either condition. Overall, these results indicate that although PACs effectively reduce PM, their impact on cognitive performance remains uncertain and may vary with PM source type, concentration, exposure duration, task demands, and other contextual factors.