This device uses a ‘four-stage’ filtration system similar to the Winix 5500-2. Like that model, this filter system comprises three physical stages and a particle ionizer. 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 is small and won’t really have much of an impact on high VOC levels. That said, its filter system is a little more rudimentary, with a smaller HEPA filter and an activated carbon sheet filter instead of the pellet type found in the 5500-2, which yields a larger effective surface area. The C545’s ionizer imparts a negative charge on fine particles. It causes them to clump together and fall to the ground, though this process does release ozone as a byproduct, a respiratory irritant. As per the manufacturer, the amount of ozone released from the device’s ‘PlasmaWave’ ionizer is nominal and won’t surpass the safe concentration of 0.05 ppm. If you don’t want to use the ionizer, you can turn it off. In testing, we observed a drop in 0.3 µm particle concentration with the ionizer turned on, but it had very little impact on the device’s air cleaning rate.

You’ll need to vacuum off any stuck-on debris from the pre-filter every 14 days. If it’s especially soiled, you can rinse it under room temperature water, but make sure not to use any detergent or soap and to let it dry for at least 24 hours before reinstalling it. It isn’t intended to be replaced.

The True HEPA and activated carbon filters aren’t washable. The HEPA filter has a lifespan of a year, while the carbon filter needs to be replaced every three months. A replenishment pack contains a single HEPA and four carbon filters and can be purchased here.