Purifier marketing loves to blur two very different technologies. Understanding the difference saves you money and protects your lungs.
How HEPA works A true HEPA filter is a dense mat of fibers that physically traps particles as air is forced through it. It captures 99.97 percent of particles at 0.3 microns, the hardest size to catch, and does even better on larger and smaller particles. The captured pollen, dust, and dander stay locked in the filter until you replace it. The tradeoff is that HEPA needs a fan and the filters cost money over time.
How ionizers work Ionizers release charged ions that attach to airborne particles, making them clump and fall onto surfaces or stick to a collector plate. The particles leave the air, but they often land on your furniture and can re-enter the air when disturbed.
The ozone problem Many ionizers, and all ozone generators, produce ozone as a byproduct. Ozone is a lung irritant. The EPA has repeatedly warned that ozone-producing air cleaners can worsen asthma and respiratory issues. For a device meant to help you breathe, that is a serious flaw.
Our recommendation - Choose a true HEPA purifier as your primary cleaner. - Treat any built-in ionizer as optional, and leave it off, especially if anyone in the home has asthma. - Never buy a standalone ozone generator for occupied spaces.
HEPA is boring, proven, and effective. Ionizers are flashier and riskier. For clean air you can trust, boring wins.