Air purifiers are designed to clean indoor air—but how they do it, and how effectively they work, can vary significantly depending on the technology used.
At a basic level, most air purifiers draw air into the system, pass it through one or more filters, and then recirculate cleaner air back into the room. But the type of filtration—and how it interacts with different pollutants—determines what is actually removed from the air.
Understanding these differences can make it easier to identify which systems are designed for comprehensive air cleaning—and which rely on more limited or situational technologies.
How HEPA and carbon filters capture pollutants
The foundation of most air purifiers is the HEPA (High-Efficiency Particulate Air) filter, which physically traps airborne particles, including dust, pollen, pet dander, mold spores, and even many viruses and bacteria. HEPA filters work through three mechanisms:
- Interception: Particles stick to the filter fibers as air passes through.
- Impaction: Larger particles collide with fibers and become embedded.
- Diffusion: Ultrafine particles are slowed and captured by the dense filter matrix.
HyperHEPA filters are designed to capture 99.95% or more of all airborne particles, including ultrafine particles – those measuring less than 0.1 microns in diameter.
For gases, odors, and volatile organic compounds (VOCs) from sources like cleaning products, cooking, or new furniture, activated carbon filters are essential. These filters contain millions of tiny pores that chemically bond with and absorb gaseous pollutants, neutralizing smells and harmful chemicals that HEPA filters cannot capture.
Together, HEPA and carbon filters provide broad protection against both particulate and gas-phase pollution.
UV, ionizers, and other technologies
Some air purifiers include additional technologies intended to enhance air cleaning—but their effectiveness and safety can vary:
- UV-C light: Used to neutralize bacteria, viruses, and mold spores by damaging their DNA, UV-C does not remove either particles or gases on its own. However, UV systems must be fully contained within the purifier to avoid exposing occupants to harmful radiation or ozone.
- Ionizers: These emit charged ions that attach to airborne particles, making them heavier so they settle out of the breathing zone or stick to surfaces; consequently, the particles can become airborne once more if disturbed. Ionizers are not effective for larger pollutants like pollen or dust, and many produce ozone – a lung irritant and pollutant – as a byproduct.
- Electrostatic precipitators: Similar to ionizers, these charge particles and collect them on oppositely charged plates. Electrostatic precipitators also generate ozone and require frequent cleaning to maintain efficiency.
- Ozone generating air purifiers: These are illegal in California and strongly discouraged by the U.S. Environmental Protection Agency, due to ozone’s impact on human health (1)(2).
All of the above technologies can emit ozone, a pollutant and the main ingredient in smog.
Filtration systems that combine HyperHEPA and activated carbon are widely considered among the most effective approaches, especially when paired with smart sensors that adjust fan speed based on real-time air quality.
In practical terms, this means filtration-based systems remove pollutants from the air, while some other technologies may only alter or redistribute them.
Frequently Asked Questions
Do air purifiers remove viruses and bacteria?
Yes. HEPA filters capture most airborne viruses and bacteria.
Can an air purifier remove odors from cooking or pets?
Yes. Activated carbon filters are specifically designed to absorb odors and VOCs from cooking, pets, smoke, and chemicals, leaving the air fresher.
Are ionizers safe to use in homes?
Most ionizers produce ozone, which can irritate lungs and worsen respiratory conditions. HEPA-based purifiers are a safer choice, especially for sensitive individuals.
How often should I replace the filters?
HyperHEPA filters typically last 36–48 months, while the gas and odor filtering V5-Cell may need replacement every 12–18 months, depending on usage and air quality.
Conclusion
Air purifiers work by combining proven filtration technologies—primarily HEPA and activated carbon—to remove a broad spectrum of indoor air pollutants, from fine particles to harmful gases. Other technologies like UV or ionization introduce risks like ozone exposure.
For consistent and comprehensive air cleaning, filtration-based systems—particularly those using HyperHEPA and activated carbon—are typically the most reliable.
