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Ozone generators & Ozone based air purifiers & air cleaners:
Do ozone generators and air purifiers work? Are ozone generators, mold treatments, deodorizers, and air purifiers recommended? As reported by the U.S. EPA, ozone generators that are sold as air cleaners intentionally produce the gas ozone.
Often the vendors of ozone generators make statements and distribute material that lead the public to believe that these devices are always safe and effective in controlling indoor air pollution. Page to photo: one of our ozone gas detector test instruments using a Draeger bellows pump and a colorimetric gas sampling tube.
For almost a century, health professionals have refuted these claims (Sawyer, et. al 1913; Salls, 1927; Boeniger, 1995; American Lung Association, 1997; Al-Ahmady, 1997). The purpose of this document is to provide accurate information regarding the use of ozone-generating devices in indoor occupied spaces. This information is based on the most credible scientific evidence currently available.
In inspecting and testing many buildings we often encounter both owners and consultants who try to solve an existing problem by treating the symptom (for example an odor) rather than by treating the cause (a dead animal, for example, or insufficient fresh air intake, for another example).
The proper way to get rid of an indoor mold problem is to remove the problem mold and correct the conditions that caused it to grow. Attempts to rely on odor killers, mold killers, deodorants, or ozone generators are futile and may be harmful. Details follow.
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Ozone-generating Air Cleaners are NOT RECOMMENDED to Purify Indoor Air and NOT RECOMMENDED as a Mold Treatment
Ozone Indoors - Bottom line:
At airborne concentrations of ozone which are safe, that is, are unlikely to be a hazard to humans, ozone is ineffective at removing contaminants. At high levels in indoor air, ozone is likely to be hazardous to building occupants, and in our direct experience its use at high levels indoors can lead to surprise chemical reactions and oxidations of other building materials that in turn lead to new indoor odor, VOC, and other problems.
Notice: our discussion of the ineffectiveness of ozone as an indoor air cleaner and the potential hazards of indoor use of ozone for deodorizing, cleaning, or killing mold, is focused on the issues surrounding ozone and equipment that produces it indoors. AHAM , The Association of Home Appliance Manufacturers, certifies the effectiveness of various types of portable air cleaners.
Some vendors suggest that ozone-generating devices have been approved by the federal government for use in occupied spaces. This is not the case.
Watch out: The U.S. EPA emphasizes in its own publications that
Because of these claims, and because ozone can cause health problems at high concentrations, several federal government agencies have worked in consultation with the U.S. Environmental Protection Agency to produce this public information document.
The same chemical properties that allow high concentrations of ozone to react with organic material outside the body give it the ability to react with similar organic material that makes up the body, and potentially cause harmful health consequences. When inhaled, ozone can damage the lungs (see - "Ozone and Your Health" - www.epa.gov/airnow/brochure.html ). Relatively low amounts can cause chest pain, coughing, shortness of breath, and, throat irritation.
Ozone may also worsen chronic respiratory diseases such as asthma and compromise the ability of the body to fight respiratory infections. People vary widely in their susceptibility to ozone. Healthy people, as well as those with respiratory difficulty, can experience breathing problems when exposed to ozone.
Exercise during exposure to ozone causes a greater amount of ozone to be inhaled, and increases the risk of harmful respiratory effects. Recovery from the harmful effects can occur following short-term exposure to low levels of ozone, but health effects may become more damaging and recovery less certain at higher levels or from longer exposures (US EPA, 1996a, 1996b).
Manufacturers and vendors of ozone devices often use misleading terms to describe ozone. Terms such as "energized oxygen" or "pure air" suggest that ozone is a healthy kind of oxygen. Ozone is a toxic gas with vastly different chemical and toxicological properties from oxygen. Several federal agencies have established health standards or recommendations to limit human exposure to ozone.
Ozone-generating Air Cleaners Used to Remove Odors May Produce Excessive levels of Ozone Gas and May Cause Problematic Chemical Reactions with Other Building Contents
Ozone is a highly toxic gas but even highly toxic substances can be encountered safely. The main concern with this material is that concentrations to which people are exposed do not average more than 0.1 ppm over an 8-hr day, and do not exceed that value by more than a factor of 2 or 3 during the exposure." 
While expert use of ozone can be successful in some deodorizing applications, we have received primarily complaints from people who tried using ozone to get rid of indoor odors only to find that they had made things worse.
Question on Getting Rid of New Smells After Using an Ozone Generator Indoors:
We have investigated a number of post-ozone treatment complaints and have been able to resolve the problem successfully, but not always at low cost. Ozone gas itself is very reactive - an oxidant. It does not stay around long after it has been generated in a building unless there is a continuing source such as an ozone generator still at work.
But when high levels of ozone have been produced in an enclosed space, we find that other materials in the space become partly oxidized, subsequently giving off horrible, often chemical-like odors. We have traced odors to painted surfaces, furniture, upholstery, curtains, carpeting, carpet padding, and other materials.
Try making a smell-patch test - see SMELL PATCH TEST to Track Down Odors to determine just which building component has been oxidized. Following this procedure we can often narrow down the source of post-ozone-treatment smells to a single material that can then be removed or remedied, such as carpet padding or a specific piece of furniture. More about tracking down odors in buildings is at ODORS, Smells, Gases in Buildings-Diagnosis & Cure.
The following data is obtained from "Ozone-Generating Air Cleaners and Indoor Air Chemistry" , a U.S. EPA Document
Continue reading at OZONE GENERATORS for INDOOR AIR POLLUTION or select a topic from the More Reading links shown below.
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Frequently Asked Questions (FAQs)
Question: Apartment manager treated my apartment with ozone generator, ruined carpet, killed my plants, I have chest pain
I was told by an apartment manager when I moved in to my new apartment that it was a smoke free facility and when I was ready to move in,I went in the apartment they had for me and it smelled of cigarette smoke. I told her that I had allergies to cigarette smoke, so I couldn't move in and she said that they would repaint and clean the carpet so that I could move in.
Originally she told me that if any of the residents had smoked in their apartments that they would replace the carpet and they didn't do that for me. What I found out later is that there had been two chain smokers that had lived in this apartment. So they said they would put an ozonator in here and that the smell would go away and said it was okay for me to be in the apt while it was on.
I have had chest pain on my right lung now for three months and have no energy and am having a very hard time seeing specialists because of this. She told me that they would not replace the carpet when I moved in because they had just replaced it when earlier she told me that they would. All she has done since I have been here is lie to me. DO NOT USE AN OZONATOR AND BE PRESENT AND REMOVE ALL PLANTS AS MY BIG FIG TREE LEAVES TURNED BLACK. SO WHAT DO YOU THINK IT HAS DONE TO MY LUNGS?????? - Jan-Marie 3/15/12
For our opinion & advice on determining if you have been injured by ozone exposure, see our suggestions at 3 Steps to Assessing Possible Harm from Exposure to Ozone Gas O3.
As we replied to Josh in that Q&A, by no means do we advocate panic about ozone exposure, but it is quite evident that some applications of ozone make sense and others do not. There we also note the ozone issues arising from over-dosing or over-exposing building interiors and contents just as you describe. Details about oxidizing damage from over-doing an ozone treatment are at OZONE TOXICITY.
Questions & answers or comments about using ozone generators in buildings as general air cleaners & who does or does not recommend their use.
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Technical Reviewers & References
Allergies, Allergens, Allergy Testing in Buildings - References & Products
Mold Contamination Testing, Cleanup, Prevention: references & products
OTHER IAQ ISSUES: How To Find and Address Other Indoor Air or Indoor Environment Contaminants Besides Mold
Mold or allergens may not be the only or even the main indoor environmental contaminant. Don't let media attention to mold cause so much enviro-scare fear that other, possibly more urgent hazards go un-addressed.