Ozone generators are not air cleaners.

Have you been approached by sales people or seen a marketing ad stating that their air cleaning machine makes “activated oxygen” or refreshes the air “like a thunderstorm”. These terms give an impression that breathing ozone is good. In reality, the opposite is true.

In the past, manufacturers of ozone generators made unsubstantiated claims about the benefits of their products that included improving health through killing airborne mold and destroying common organic compounds. Since that time, several governmental agencies and professional organizations have confronted the manufacturers to challenge their claims. As a result, manufacturers of the ozone machines have changed how the devices are marketed. However, introducing ozone into homes, offices and other occupied spaces is still being touted as an effective way of “purifying” indoor air. It doesn’t matter how these devices are advertised or what terminology is used, the problems associated with using ozone in an occupied building remain:

Ozone is regulated both indoors and out because it is a highly potent oxidizer–even at modest levels, it burns the eyes, nose, throat, sinuses and lungs.

One manufacturer recently advertised that its “…air purifiers produce ozone levels which fall a full 20% below FDA and OSHA safe limits…” This statement is misleading because OSHA limits are intended for healthy adult employees in a manufacturing setting, and whose exposure to ozone is limited to no more than 40 hours per week. It appears manufacturers are applying the OSHA limit to the general population, which includes infants and the elderly, and those who may be exposed on a 24/7/365 basis.

Many manufacturers continue to claim that ozone reacts with organic compounds in the air to form harmless carbon dioxide and water. In fact, it is more likely that the organic compounds will be converted to chemicals that are more hazardous. In one study, the reaction of ozone with airborne organic compounds produced a variety of aldehydes (e.g., formaldehyde) and the total amount of organic compounds in the air actually increased rather than decreased. Because of this concern, the EPA is currently studying the types of chemicals that are formed when common organic compounds react with ozone. The amount of ozone produced by these devices is insufficient to kill microorganisms such as mold and bacteria.

According to the U.S. FDA, ozone must be present at concentrations far greater than that which people and animals can safely tolerate in order to be effective as a germicide.

And since mold spores are generally much hardier than bacteria or viruses, a much higher concentration is needed to kill mold.

The facts are simple: Ozone is a toxic compound that has no known health benefit and does not purify indoor air at concentrations tolerated by people.


Bob Beisbier, owner of BK Home Inspection, is a Certified Master Home Inspector who has been providing professional and thorough home inspections in southeast Wisconsin for over 12 years. Bob is Infrared certified, DILHR Certified, and provides Home Energy Tune-ups, Environmental Data Reports, Pre-sale Home Inspections and Pre-offer Home Inspections.