When sourcing car air purifiers, prioritize units with True HEPA filters (H13 grade) which can capture 99.97% of particles as small as 0.3 microns, including pollen and dust. For B2B buyers targeting urban markets, ensure the device includes an Activated Carbon layer to effectively neutralize VOCs, exhaust fumes, and cigarette odors. For premium segments, look for Negative Ion (Anion) generators that help precipitate airborne particles, but verify they are Ozone-free (UL 867 certified) to ensure passenger safety.