While the manufacturer advertises this air purifier as having a four-stage filtration system, it only has three physical layers of filtration. There’s a mesh pre-filter for trapping larger particles, a HEPA filter, and a Carbon filter for minimizing odors and VOCs. However, like most consumer-grade air purifiers, the amount of activated carbon within is too little to have a significant impact. Its nominal fourth stage is the device’s built-in ‘PlasmaWave’ ionizer. This system releases negative ions into the air that impart an electrical charge to small particles, causing them to clump together and fall to the ground or any other flat surface, where you can easily clean them up with a rag or vacuum. The main downside of ionizers is that they naturally produce ozone, which can irritate your respiratory system. It’s worth noting that Winix claims that their ‘PlasmaWave’ ionizer produces well under the nominally safe concentration of 0.05 ppm. Regardless, if you don’t want to use the ionizer, you can turn it off; from our own testing, the ionizer didn’t have too large of an impact on air purification performance anyways.

You’ll need to clean the pre-filter under water or vacuum off any stuck-on debris and dust every 14 days; just make sure not to use any detergent or soap. If you rinse the pre-filter, let it dry for at least 24 hours before reinstalling it. You aren’t meant to replace it.

The HEPA filter isn’t washable, but you should replace it every 12 months. You can rinse the activated carbon filter, but don’t wash it with soap or water. Like the pre-filter, it must dry for at least 24 hours before you reinstall it. The carbon filter has an estimated lifespan of 12 months. The HEPA and carbon filters are sold in a single pack and can be purchased here.