Air purifiers vs ionizers | Live Science

We pit air purifiers against ionizers to get to the bottom of what each appliance really does.

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Air pollution can be a problem both outdoors and indoors. Indoor air can contain dust, bacteria, viruses, pollen and pet dander, as well as particles released by cosmetics and cleaning products. Many people strive to eliminate these allergens and pollutants with appliances like air purifiers and ionizers.

But what is the difference between air purifiers and ionizers? Broadly speaking, they both take allergens and other pollutants out of the air. However, the way they do so is very different.

Air purifiers may also have different implications for our health than ionizers, and vice versa, Dr. Payel Gupta, an assistant professor at New York’s SUNY Downstate Medical Center and a national spokesperson for the American Lung Association, told Live Science.

Air purifiers capture pollutants, toxins and allergens in the air using a fan and at least one filter. The internal fan pulls air from the room in over the filter, and particles are captured within the filter's many layers and pleats. Once that process is complete, clean air is recirculated in the room.

The United States Environmental Protection Agency (EPA) says that air purifiers with high-efficiency particulate air (HEPA) filters can hypothetically remove at least 99.97% of airborne particles that measure as small as 0.3 microns. "HEPA filters can trap fine particulate matter found in traffic pollution and smoke," Gupta said.

Many of the best air purifiers are also equipped with additional filters and other features designed to reduce the amount of harmful particulate matter in the air. "For example, carbon filters can absorb volatile organic compounds (VOCs) and odors from smoke, further improving indoor air quality," said Gupta.

Ionizers, on the other hand, purify the air in the room by creating negative ions, which are electrically charged particles. "[These] charged ions then attach to particles, causing them to clump together and fall out of the air or be attracted to surfaces," Gupta said.

Put simply, ionizers create dense particles that are heavy enough to fall to the floor, so from there, they still need to be cleaned up. This also means the clumped-up particles can easily be disturbed and reintroduced into the air. Compared to ionizers, air purifiers work on a wider range of particle sizes, from large allergens like dust and pollen to smaller ones such as pet dander, bacteria and viruses. Ionizers tend to work best on small particles, but they're ineffective at removing larger particles like dust and pollen, according to the EPA.

Ionizers do have one big drawback, Gupta said. "Many ionizers produce ozone as a by-product, which can irritate the respiratory system and exacerbate asthma and allergies in sensitive individuals," she said. Ozone is a gas made up of trios of oxygen atoms, and children, older people and people with pulmonary issues face the highest risks from breathing it in.

In the short term, the EPA says that inhaling small amounts of ozone could lead to throat irritation, chest pain, coughing, shortness of breath or difficulty breathing. Long-term effects can include worsening asthma symptoms, a decrease in lung function and lung inflammation.

Ultimately, neither air purifiers nor ionizers are the perfect solution to air pollutants.

"You can clean air to a certain extent, but you can never truly purify it," Gupta said. "[These appliances] are most effective when combined with efforts to minimize outdoor air pollution and improve overall ventilation."

This article is for informational purposes only and is not meant to offer medical advice.

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Kerry is a freelance writer and editor, specializing in science and health-related topics. Her work has appeared in many scientific and medical magazines and websites, including Forward, Patient, NetDoctor, YourWeather, the AZO portfolio, and NS Media titles.

Kerry’s articles cover a wide range of topics including astronomy, nanotechnology, physics, medical devices, pharmaceuticals and mental health, but she has a particular interest in environmental science, cleantech and climate change.

​​​Kerry is NCTJ trained, and has a degree Natural Sciences from the University of Bath where she studied a range of topics, including chemistry, biology, and environmental sciences.

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