The frequency of filter replacement is closely tied to factors such as the density of particulate matter (PM) in the environment, room size, natural air exchange rate through windows, and the operating voltage of the air purifier.
In an environment with an average PM2.5 level of 10 µg/m³, filters typically need to be replaced every nine months. However, if PM2.5 levels rise to 90 µg/m³ during wildfire season, replacement may be necessary every month.
It is generally advised to replace the filter at least once a year.