Ozone Safe: Only 0.006ppm, 1/8th the Legal Limit

What Intertek measured

In 2025, Intertek tested the WellisAir WADU-02 under UL 867 Section 40, the standard that governs ozone emissions from air cleaners.

  • 0.006 ppm maximum ozone concentration — and 0.002 ppm on the high fan setting
  • 0.005 ppm averaged over eight hours
  • Measured both with and without the cartridge fitted; 0.006 ppm is the figure with it in
  • The legal limit under UL 867 and CARB is 0.050 ppm

WellisAir is a CARB certified air cleaning device, listed by the California Air Resources Board — the strictest ozone regime in the United States.

Why this matters

Ozone at the levels produced by ozone generators irritates the eyes, nose and throat, reduces lung capacity, triggers asthma symptoms and can damage lung tissue over time. The EPA is explicit that ozone generators sold as air cleaners should not be used in occupied spaces.

That is exactly why the number matters. An ozone generator works by filling a room with ozone, and the room has to be empty while it runs. WellisAir is not that kind of device: at 0.006 ppm it is designed to run with people, pets and children in the room, continuously.

If you are comparing air cleaners, ask every manufacturer for a UL 867 ozone figure from a named laboratory. Many will not have one.

How WellisAir cleans the air instead

WellisAir works by releasing hydroxyl radicals — the same short-lived molecules that clean the Earth’s atmosphere every day, often called nature’s detergent. Hydroxyls break down odors, smoke gases and volatile organic compounds by pulling a hydrogen atom away from them, leaving water vapor behind.

It has no filter and no UV lamp. One unit covers up to 1,000 sq ft, draws 3.6 watts and runs below 30 dB.

Learn More About Hydroxyl Technology →

Ozone questions, answered

Does WellisAir produce ozone?

It produces a trace amount, far below the legal limit. Intertek measured 0.002 to 0.006 ppm depending on fan speed in 2025 under UL 867 Section 40 (report 106174008CRT-002), against a limit of 0.050 ppm set by UL 867 and the California Air Resources Board.

Is WellisAir an ozone generator?

No. An ozone generator deliberately fills a room with ozone as its cleaning method, and the room must be unoccupied while it runs. WellisAir cleans the air with hydroxyl radicals and is designed to run continuously in occupied rooms. Its measured ozone output is 0.006 ppm, about one eighth of the legal limit.

Is it safe to run around children and pets?

It is designed for continuous use in occupied rooms, with ozone output about one eighth of the legal limit and CARB certification. As with any air treatment device, if anyone in the home has a respiratory condition or a known sensitivity to fragrance or chemical emissions, discuss it with their doctor first — and note that the citrus cartridge contains d-limonene, a natural orange-peel extract that some people are sensitive to. An unscented cartridge is available.

Is WellisAir CARB certified?

Yes. WellisAir is a CARB certified air cleaning device, listed by the California Air Resources Board. California operates the strictest ozone regime for air cleaners in the United States, and devices sold there must be certified.

Hydroxyl generator or ozone generator — which is safer?

They are different technologies. Ozone generators work by producing ozone at concentrations intended to oxidize contaminants, which is why they must be used in empty rooms and why the EPA warns against using them in occupied spaces. Hydroxyl-based devices such as WellisAir work by releasing hydroxyl radicals, which react with contaminants and leave water vapor. WellisAir’s measured ozone output is 0.006 ppm.

What does the EPA say about ozone and air cleaners?

The EPA cautions that ozone generators sold as air cleaners can produce ozone at levels that may be harmful, and advises against using them in occupied spaces. That guidance is the reason we publish our UL 867 test results: it is the only way to tell one kind of device from another. Our 2025 result is 0.006 ppm against a 0.050 ppm limit.

How does WellisAir compare with a HEPA purifier on ozone?

A HEPA purifier is a fan and a filter, so it produces no ozone at all; its limitation is that it only removes what passes through the filter and does nothing about odors or gases. WellisAir produces 0.006 ppm, a small fraction of the legal limit, and works on odors, smoke gases and VOCs in the air and on surfaces. The two are complementary, and many customers run both.

Do I need to leave the room while it runs?

No. It is designed to run 24 hours a day with people and pets present. That is the practical difference between a hydroxyl device and an ozone generator.

The test reports

  • Intertek ozone test, 2025

    UL 867 Section 40, report 106174008CRT-002. Between 0.002 and 0.006 ppm depending on fan speed, and 0.005 ppm as the highest eight-hour average, against a 0.050 ppm limit. Tested both with and without the cartridge fitted. This is the current test of the current unit.

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  • Intertek ozone test, 2018

    The earlier test of an earlier version of the unit, recording a maximum of 0.015 ppm — also well within the 0.050 ppm limit. Published for completeness; the 2025 result supersedes it.

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