We tested the DIY HEPA filter for 200 days on its cleaning efficiency. Around Day 100, effectiveness dropped 4%. Around Day 170, effectiveness dropped another 5-10%. At Day 200, effectiveness dipped to just below 50%.
So we recommend changing the HEPA filter every 140 days (8 hours a day), or every 1,000 hours. You can adjust the number based on how many hours you use it per day and how polluted your area is.
The area of the filter is a decisive factor of the HEPA lifespan. Our other HEPA filter lifespans are tested and calculated based on this original test.
Click here to read more on the raw data and more details: https://smartairfilters.com/en/blog/hepa-longevity-test-day-200/