If you use an air purifier that does not indicate when the filters need replacing, how do you (you specifically) tell when you need to replace them?

*I'm asking what you do, not for random men to yell at me. lol

I'd love to know how people handle this.

We're thrilled to announce that we've received a grant from the Balvi Foundation to advance our open-source air purifier!

This funding supercharges our mission to provide clean air for all, tackling COVID-19, wildfire smoke, and more.

https://airsupportproject.com/breathing-innovation-air-support-projects-fan-and-filter-open-source-prototype-receives-funding-from-the-balvi-foundation/