Ozone Air Cleaners or air Purifiers - are Not Generally Recommended for Indoor Air Cleaning InspectAPedia® -
US EPA and other experts do not recommend use of ozone-generating "air purifiers" or "air cleaners" as a means to attempt to purify, deodorize, or otherwise treat indoor air
The effects of using ozone in buildings to "purify air" or to "kill mold"
The toxicity of ozone gas and ozone gas exposure limits
The hazards of ozone generators in buildings
Questions & answers about using ozone generators in buildings as general air cleaners
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.
InspectAPedia offers impartial, unbiased advice without conflicts of interest.
We will block advertisements which we discover or readers inform us are associated with bad business practices,
false-advertising, or junk science. Our contact info is at
InspectAPedia.com/Contact.htm.
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 best ways to get rid of an indoor odor or airborne particle contaminant are:
Find and remove the odor source or problem particle source (such as dust, pet allergens, mold).
Make sure there is adequate fresh air intake for the building
Use high quality air filtration to reduce the level of circulating dust indoors.
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.
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. The U.S. EPA emphasizes in its own publications that NO agency of the federal government has approved these devices for use in occupied spaces. 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.
How is Indoor Ozone Gas Harmful to People
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." [1]
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:
I was hoping that you may have some suggestions on how to rid a house of the left over odor or chemicals, from using an ozone generator.
It's a long story, but I used a high powered ozone generator in my house, to get rid of skunk smell. Now I can't get rid of the left over nitric oxide, or whatever odor or gases, that linger in my house. I have been leaving the windows open every day, with running the heat on high (85 degrees) at night, to try to force off-gas the odors/gases.
All I can find is where others have had the same thing happen, and they ended up having to leave their homes. we are still hoping I can find a way to rid my house of the problem. - Nadine -
Answer:
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.
Ozone-Generating Air Cleaners and Indoor Air Chemistry
The following data is obtained from "Ozone-Generating Air Cleaners and Indoor Air Chemistry" , a U.S. EPA Document
Ozone-generating air cleaners are marketed to homeowners as well as business establishments ostensibly to remove odors and other contaminants from indoor air. IEMB has characterized ozone and oxides of nitrogen (NOx) emissions from these devices in full-scale environmental chamber tests and characterized performance in a research test house.
To date, findings demonstrate that, for those models tested, ozone generation rates are generally within the ranges stated by the manufacturers and some models have the capacity to generate ozone concentrations of 200 parts per billion (ppb) in the test house, well above EPA's 8-hour ambient ozone standard of 80 ppb.
Additionally, ozone and nitrogen dioxide emission rates increase with decreasing relative humidity, and the relationship between ozone emission rate and NOx generation rate varies between different models of different manufacturers.
Ozone-generating air cleaners equipped with an ozone sensor/controller designed to prevent activation of the ozone generator at concentrations above 50 ppb performed erratically in full-scale chamber tests but appeared to perform as designed in limited short-term (24 h) tests in a research test house.
We [the U.S. EPA] conclude that more extensive testing is needed to characterize the sensor/controller. However, tests in the research test house clearly demonstrate that these devices are capable of producing ozone concentrations well above those of accepted health guidelines.
IEMB is currently investigating the impact of ozone generators on concentrations of volatile organic compounds (VOCs) in indoor environments. These experiments investigate the chemical reactions that take place when an ozone-generating air cleaner is operated in the presence of emissions from a typical source of VOCs, such as an air freshener or cleaning product.
Results demonstrate that the ozone-generating air cleaners have little impact on airborne concentrations of solvents used in consumer products, but do impact concentrations of many of the fragrance compounds emitted by this type of product.
Reaction products include formaldehyde and other oxygenated organics. The interaction between ozone and some of the product emissions, such as terpenes, triggers formation of ultra fine particles. IEMB is currently refining analytical approaches to better characterize the "soup" of particles and gases that results from operation of these devices in the presence of VOCs.
Critique, contributions wanted: Contact Us to suggest corrections or additions to articles at this website, and if you wish, to receive online listing and credit as a contributor. Particular thanks are due to the many experts and also consumers who read and critique technical articles at InspectAPedia.com.
Additional technical contributors & reference sources for this article are listed below.
Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.
"Ozone-Generating Air Cleaners and Indoor Air Chemistry" , U.S. Environmental Protection Agency, original document is available at: epa.gov/appcdwww/iemb/ozone.htm
"Ozone Generators that are Sold as Air Cleaners", U.S. Environmental Protection Agency, original document is available at: epa.gov/iaq/pubs/ozonegen.html "EPA reviewed a wide assortment of this literature, including information provided by a leading manufacturer of ozone generating devices. In keeping with EPA's policy of insuring that the information it provides is based on sound science, only peer reviewed, scientifically supported findings and conclusions were relied upon in developing this document."
Association of Home Appliance Manufacturers (AHAM) 1111 19th Street, NW, Suite 402, Washington, DC 20036, (202) 872-5955 www.aham.org provides information on air cleaners on their AHAM-certified Clean Air Delivery Rate site at www.cadr.org AHAM conducts four certification programs for each category - room air cleaners, room air conditioners, dehumidifiers and refrigerator/freezers. The air cleaner certification program is known as AC-1.
U.S. EPA- Indoor Air Quality Information Clearinghouse (IAQ INFO), PO Box 37133, Washington D.C. 20013-7133; by phone (800) 438-4318.
California Department of Health Services, Indoor Air Quality Program, 850 Marina Bay Parkway, Suite G365/EHL, Richmond, CA 94804. DHS-IAQ Program Assistance Line: (510) 620-2874, Fax: (510) 620-2825
Thanks to reader Nadine - for a field report of use of an ozone generator to remove a skunk smell - Feb 2009.
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
Kansas State University, department of plant pathology, extension plant pathology web page on wheat rust fungus: see http://www.oznet.ksu.edu/path-ext/factSheets/Wheat/Wheat%20Leaf%20Rust.asp
"A Brief Guide to Mold, Moisture, and Your Home",
U.S. Environmental Protection Agency US EPA - includes basic advice for building owners, occupants, and mold cleanup operations. See http://www.epa.gov/mold/moldguide.htm
Allergen Tests in Buildings advice about how to test, what to look for, in evaluating the level of dog, cat, or other animal allergens in a building
"IgG Food Allergy Testing by ELISA/EIA, What do they really tell us?" Sheryl B. Miller, MT (ASCP), PhD, Clinical Laboratory Director, Bastyr University Natural Health Clinic - ELISA testing accuracy: Here is an example of Miller's critique of ELISA
http://www.betterhealthusa.com/public/282.cfm - Townsend Letter for Doctors and Patients
The critique included in that article raises compelling questions about IgG testing assays, which prompts our interest in actually screening for the presence of high levels of particles that could carry allergens - dog dander or cat dander in the case at hand.
http://www.tldp.com/issue/174/IgG%20Food%20Allergy.html contains similar criticism in another venue but interestingly by the same author, Sheryl Miller. Sheryl Miller, MT (ASCP), PhD, is an Immunologist and Associate Professor of Basic and Medical Sciences at Bastyr University in Bothell, Washington. She is also the Laboratory Director of the Bastyr Natural Health Clinic Laboratory.
Allergens: Testing for the level of exposure to animal allergens is discussed at http://www.animalhealthchannel.com/animalallergy/diagnosis.shtml (lab animal exposure study is interesting because it involves a higher exposure level in some cases
Allergens: WebMD discusses allergy tests for humans at webmd.com/allergies/allergy-tests
Animal Allergens: Dog, Cat, and Other Animal Dander - Cleanup & Prevention Information for Asthmatics and regarding Indoor Air Quality.
Recognizing Allergens: What various indoor allergens look like - identification photos to help identify pollen, dust mites, animal dander, toxic or allergenic mold - Common Mold and other Allergens, Irritants, Remedies & Advice
Rodent control issues, including dander, fecal, and urine contamination of Buildings and Building insulation are discussed at our
Associations: Sick House, Sick Building, SBS - Air Quality, Government, Private Associations and Information Resources
Atlas of Clinical Fungi, 2nd Ed., GS deHoog, J Guarro, J Gene, & MJ Figueras, Centraalbureau voor Schimmelcultures, Universitat Rovira I Virgili, 2000, ISBN 90-70351-43-9 (you can buy this book at Amazon)
Atlas of Indoor Mold, Online Clinical Mold Atlas, Toxins, Pathogens, Allergens and Other Indoor Particles - Medical Health Effects of Mold (separate online document)
Black Mold that is Harmless Photos of recognizable, usually harmless black mold on wood, bluestain, ceratocystis, ophistoma
Building Floods: quick steps after a building flood or plumbing leak can prevent costly mold contamination
Classes of Mold: what types of cosmetic, allergenic, or toxic mold are a problem? Can mold be cleaned-up successfully?
"A Brief Guide to Mold, Moisture, and Your Home", U.S. Environmental Protection Agency US EPA - includes basic advice for building owners, occupants, and mold cleanup operations. See http://www.epa.gov/mold/moldguide.htm
"Disease Prevention Program for Certain Vegetable Crops," David B. Langston, Jr., Extension Plant Pathologist - Vegetables, University of Georgia (PDF document) original source: www.reeis.usda.gov/web/crisprojectpages/209797.html
"Disease Prevention in Home Vegetable Gardens,"
Patricia Donald,
Department of Plant Microbiology and Pathology,
Lewis Jett
Department of Horticulture, University of Missouri Extension - extension.missouri.edu/publications/DisplayPub.aspx?P=G6202
Fifth Kingdom, Bryce Kendrick, ISBN13: 9781585100224, is available from the InspectAPedia online bookstore - we recommend the CD-ROM version of this book. This 3rd/edition is a compact but comprehensive encyclopedia of all things mycological. Every aspect of the fungi, from aflatoxin to zppspores, with an accessible blend of verve and wit. The 24 chapters are filled with up-to-date information of classification, yeast, lichens, spore dispersal, allergies, ecology, genetics, plant pathology, predatory fungi, biological control, mutualistic symbioses with animals and plants, fungi as food, food spoilage and mycotoxins.
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.
Ozone Warnings - Use of Ozone as a "mold"
remedy is ineffective and may be dangerous.
Pet control - if you can't say goodbye to your bird, cat, dog, guinea pig, hamster, tropical fish, then limit the
areas they occupy and limit the airflow from that area to sleeping or other areas of the building, use allergenic
bedding, eliminate wall-to-wall carpeting, improve housecleaning including use of a HEPA-rated vacuum cleaner. For more details
see our article Dog, Cat, and Other Animal Dander - Information for Asthmatics and Indoor Air Quality
Rodents, Mice, Squirrel Control - I find high levels of mouse and rodent dander, fecal dust, and urine-contaminated dust in some buildings,
and high levels of these materials in building insulation in those locations. If you have a mouse problem, particularly if mice and their waste (fecals or urine) are contaminating
the building HVAC or building insulation, may need both steps to clean up or remove infected materials and steps to stop an ongoing
rodent problem. If squirrels are a problem, the cleanup needs to include closing off entry openings into the building. Get some
help from a licensed pest control expert.
Mobile View
The Mold Information Center: