Ozone Exposure Standards, Chemical Effects of Air Cleaners on Indoor Ozone Concentration Levels InspectAPedia® -
What is the recommended exposure limit for ozone gas?
What indoor ozone levels may be generated by residential ozone generators and air purifiers?
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 ozone gas exposure standards
Ozone gas exposure standards: this article describes allowable standards for exposure to ozone such as gases produced by ozone generators or ozone air purifiers and including the use of ozone gas generators for mold remediation.
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Ozone is widely promoted by ozone generating equipment companies and cleaning services for use in indoor
building environments to deodorize, disinfect, "kill" mold, and for "general health".
Ozone generators are also promoted for use to reduce the level of airborne particles, pollen, animal dander, and allergens,
ostensibly to improve indoor air quality for asthmatics and people with allergies.
While there are some important uses of ozone (such as for medical disinfection under controlled conditions),
in general this is an idea which ranges from bad to dangerous in the home, and it is not recommended by the U.S. EPA nor other experts/agencies whose data we have reviewed.
This article explains the effects of using ozone in buildings for these purposes
and warns consumers about misapplication of and health risks from ozone in buildings.
Because at least some of these claims are based on marketing desire, not good science, and
because ozone exposure can be both dangerous and ineffective indoors, I have
collected some information and references on this topic.
Table of Ozone Gas Exposure Effects, Risk Factors, & Standards & Limits
Ozone Gas Exposure Effects, Health Risk Factors, Limits & Standards
Health Effects of Ozone
Factors that Increase Health Risks from Ozone Exposure
Ozone Exposure Standards
Asthma aggravation or asthma attacks due to ozone exposure
Airborne ozone concentration increase means increased exposure indoors
US FDA Ozone Exposure Generation Limits: ozone output of indoor medical devices shall be no more than 0.05 ppm.
Chest pain due to Ozone exposure
Longer exposure times to ozone may increase some health effects
OSHA Ozone exposure limits (apply to workplace exposure to ozone): workers shall not be exposed to an average concentration of more than 0.10 ppm for 8 hours.
Loss of lung capacity or lung function due to ozone exposure
Higher rate of respiration - breathing faster - may increase the health effects of ozone exposure, such as exercising in an area of high ozone concentration, or people (such as infants and pets) who have a higher natural respiration rate.
NIOSH Ozone exposure limits: upper limit of 0.10 ppm, not to be exceeded at any time. (This is a recommendation).
Lung irritation / respiratory infection risk due to ozone exposure
Pre-existing conditions can increase the risk of health effects of ozone exposure such as people suffering from asthma or COPD.
U.S. EPA Air Quality Standard for Ozone: in the United States, the National Ambient Air Quality Standard for ozone is a maximum 8 hour average outdoor concentration of 0.08 ppm
Lung infection due to ozone exposure
Shortness of breath due to ozone exposure
Throat irritation & cough
Note:
The columns in this table are separate subtopics and do not cross-correlate with one another.
For ozone, that "threshold" concentration is 0.1 ppm. So long as concentrations are kept at or below that level, injury is not expected even in the most sensitive workers so long as their exposure durations coincide reasonably well with or are less than the 8 hr/day, 40 hr/wk regimen.
This "threshold" ozone gas exposure level is accepted by the American Conference of Government al Industrial Hygienists (and is called the Threshold Limit Value by that organization) and by the Occupational Safety and Health Administration, OSHA.
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Additional technical contributors & reference sources for this article are listed below.
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U.S. Clean Air Act - large PDF - epw.senate.gov/envlaws/cleanair.pdf
"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.
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.
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