The Hazards of Ozone & Ozone Gas Generators
InspectAPedia® -
Ozone Gas Exposure Hazards - A Summary of Ozone Hazards Indoors
The hazards of ozone generators in buildings
The effects of using ozone in buildings to "purify air" or to "kill mold"
Questions & answers about dangers or hazards when using ozone generators for mold or odor reduction in buildings, boats, cars, campers, trucks
This article explains the hazards associated with use of ozone gas indoors as a "mold remedy" or as an "air purifier" or as a "mold killing agent".
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Environmental testing experts and authorities such as the US EPA do not recommend use of ozone for mold "treatment". Furthermore, use of ozone indoors can be hazardous and can cause oxidation or other adverse reactions with other materials and chemicals indoors. Readers should also see Ozone Gas for additional discussion of how ozone can create problems in buildings.
OZONE GAS HAZARDS - an Overview of the Hazards of Indoor Ozone Gas
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".
And while the evidence is that ozone as a mold "treatment" is questionable (see Ozone Air Cleaners Not recommended) and while sometimes ozone "mold killing or deodorizing by ozone" causes more problems than it "solves", there are indeed many other appropriate and effective uses of ozone. Indeed dissolved ozone is used in some laundry systems as a disinfectant, typically at levels of 1.5 to 3.0 ppm. [10].
That said, This article describes the dangers of using ozone gas indoors or in vehicles or other enclosed spaces as a deodorant or as a mold treatment.
Ozone exposure levels for humans and other animals
Exposure to ozone at a level you can smell or exposure to ozone over long periods
at levels greater than 0.05 ppm for 24 hours at a time is likely to be dangerous: [2], [3] Health hazards to humans and animals occur and
can be severe at ozone levels used for indoor cleaning purposes.
At least some people
can smell levels of ozone down to 0.05 ppm. This odor-detection level is
already half-way to the recommended limit. If you are generating ozone indoors,
even at "low" levels a problem may be present. People become
desensitized to odors in a short time, perhaps 20 minutes. So if you do not
smell it, the ozone level could still be hazardous.
Problems associated with ozone gas exposure include:
[4].
Lung irritation and infection.
Breathing pain, coughing, wheezing, difficulty when
exercising.
Permanent lung damage.
Aggravation of pre-existing asthma
Increased risk of lung illnesses such as bronchitis and pneumonia
Frequently Asked Questions (FAQs) about using ozone generators for mold or odor reduction in buildings, boats, cars, campers, trucks
Can I Use an Ozone Generator or Air Purifier to Get Rid of or Kill Toxic Mold Indoors?
Use of ozone to "remove" or "kill" mold is ineffective,
not recommended, and may be dangerous. Even if ozone were applied
at a concentration and for a duration sufficient to "kill" every mold spore in
a building (which is a very dubious claim), depending on the mold
genera/species present there is a good chance that the process leaves toxic and
allergenic particles in the building.
A "dead" (or non-viable) mold spore may
not grow but it can still be a health concern. The operative proper word for
mold remediation is "clean" or "remove", not "kill." In 1997,
Dr. Karin K. Foarde of Research Triangle
Institute, tested the ability of ozone to decontaminate fungi on
building materials. At ozone levels of 9 ppm for a 23-hour exposure, ozone was
found to be ineffective. [5] (Notice that this is 90-times higher than permitted ozone exposure. Exposure at
these "deodorizing" levels would be considered extremely toxic to humans.)
This
ozone treatment procedure is not recommended by the NY City Department of Health
Guidelines on the Assessment and Remediation of Fungi in Indoor Environments. Jim Holland's article on Ozone as a "mold remediation
step" is available online [6]and is a good summary of this point. Jack
E. Peterson's 1987 excellent work "Health Hazards of some Gases" also addresses
ozone hazards but it may be harder to find so I have quoted from it at the end
of this paper.
Deodorization and cleaning claims are questionable: The apparent deodorization at high ozone levels may
be simply the effect of a general desensitization to odors in the nose of
building occupants rather than actual removal of an odor source. Ozone has been
used following building fires to "reduce" smoke odors but even in this
application it does not remove soot.
Can I use Ozone or Ozone-Based Air Purifiers to Get Rid of Indoor Odors
The answer is, maybe.
If, for example, there is a
persistent odor source (such as a dead animal, flood damage, mold in building wall and ceiling cavities),
no amount of "air treatment" of any kind will remove the problem source. There
is no substitute for the actual physical effort to find and remove the offending
source. Cleaning or removing the problem source is proper and effective. Professional use of ozone, at concentrations and durations which the applicator guarantees
will not damage building materials or cause other outgassing, may be helpful as one step in a cleaning procedure where mold is not involved.
Ozone has been used
successfully in water treatment and in disinfection of cooling towers and
possibly wastewater. However it is not a durable, reliable treatment in that O3
molecules are highly reactive and volatile and thus treated substances do not
remain so.
Use of ozone may oxidize and damage materials and
increase odor levels:>[7] If ozone is no longer
being generated in a building the presence of ozone will diminish quite
rapidly. However, other odors may remain or may even be increased.
Under What Circumstances Can Use of Ozone Indoors Lead to More Odor Problems than Before?
Because ozone is a very powerful oxidant, it may react
with (oxidize) many materials found indoors, including carpets, carpet padding
(especially rubber), other floor coverings, furniture, furniture cushion foam,
and even surface paints and finishes. A common example is ozone-oxidized rubber
carpet backing or padding. We gather from research and other studies indicate that any
material that will oxidize may be expected to react with ozone, especially
cross-linked organic molecules, especially rubber.
Use of ozone may produce dangerous airborne byproducts: In other words, attempts to use high levels of ozone
to "clean" or "deodorize" building interiors may in fact generate a second
generation of unpleasant and even dangerous outgassing which may remain,
persistent indoors, after the ozone "treatment." Examples include increased levels of indoor
formaldehyde, formic acid and other acid gases, toluene, or other toxic
chemicals.
Use of ozone may increase sub micron particulates: Attempts to use high levels of ozone to "clean" or
"deodorize" building interiors may also increase the level of extremely small
sub-micron particles which themselves can be severe respiratory irritants.
Results of some controlled studies show that concentrations of ozone considerably higher than these standards are possible even when a user follows the manufacturer’s operating instructions.
There are many brands and models of ozone generators on the market. They vary in the amount of ozone they can produce. In many circumstances, the use of an ozone generator may not result in ozone concentrations that exceed public health standards. But many factors affect the indoor concentration of ozone so that under some conditions ozone concentrations may exceed public health standards.
In one study (Shaughnessy and Oatman, 1991), a large ozone generator recommended by the manufacturer for spaces "up to 3,000 square feet," was placed in a 350 square foot room and run at a high setting. The ozone in the room quickly reached concentrations that were exceptionally high--0.50 to 0.80 ppm which is 5-10 times higher than public health limits.
In an EPA study, several different devices were placed in a home environment, in various rooms, with doors alternately opened and closed, and with the central ventilation system fan alternately turned on and off. The results showed that some ozone generators, when run at a high setting with interior doors closed, would frequently produce concentrations of 0.20 - 0.30 ppm. A powerful unit set on high with the interior doors opened achieved values of 0.12 to 0.20 ppm in adjacent rooms. When units were not run on high, and interior doors were open, concentrations generally did not exceed public health standards (US EPA, 1995).
The concentrations reported above were adjusted to exclude that portion of the ozone concentration brought in from the outdoors. Indoor concentrations of ozone brought in from outside are typically 0.01- 0.02 ppm, but could be as high as 0.03 - 0.05 ppm (Hayes, 1991; U.S. EPA, 1996b; Weschler et al., 1989, 1996; Zhang and Lioy; 1994). If the outdoor portion of ozone were included in the indoor concentrations reported above, the concentrations inside would have been correspondingly higher, increasing the risk of excessive ozone exposure.
None of the studies reported above involved the simultaneous use of more than one device. The simultaneous use of multiple devices increases the total ozone output and therefore greatly increases the risk of excessive ozone exposure.
Watch out: improper use of ozone indoors may oxidize certain plastics, leading to dangerous formation of oxides of nitrogen gases. See Nitrogen Oxides Gas for details.
Can I use Ozone or Ozone-Based Air Purifiers to Get Rid of Odors in a Car, Truck, Camper, or RV?
The answer is, maybe.
The same worries pertain about use of ozone inside vehicles as we discussed above concerning the use or over-use of ozone as an "odor killer" inside buildings. But the risks of overdoing ozone inside of a car or vehicle may be still greater for two reasons:
Using an ozone generator inside of the much smaller space of a vehicle can expose the vehicle's interior to higher ozone concentrations, leading to higher risk of over-dosing with ozone, and oxidized materials.
Most vehicles and campers use a greater quantity of plastics and synthetic materials than may be found in most buildings. So the risk of oxidizing plastic materials may be greater.
Please see our full article about odors in cars and other vehicles, found at BOAT & CAR SMELLS & ODORS.
Watch out: as we warned earlier, improper use of ozone indoors may oxidize certain plastics, leading to dangerous formation of oxides of nitrogen gases. See Nitrogen Oxides Gas for details.
Question: The Excretion of dissolved ozone in human urine?
After breathing a high dose of Ozone, is it possible to absorb it and urinate it out? As after breathing it in at my workplace, I believe I could smell it in my urine. - Anthony
Reply:
Ozone can indeed become dissolved in the human bloodstream, and Velio A Bocci et als point out that while there are effective medical uses for inhaled ozone when applied in a medically supervised [oxygen] gas mixture use, ozone may be "toxic for the pulmonary system during prolonged inhalation, continuing ... when it is chronically inhaled, [ozone] is highly toxic for the pulmonary system because the enormous alveolar surface, unprotected by sufficient antioxidants, is exposed to the cumulative ozone dose, which causes a chronic inflammation." [11].
As for ozone being dissolved in urine, presumably removed from blood and excreted through the kidneys, the same authors point out risks of kidney damage from ozone. But we have not found an authoritative source indicating the olfactory detection of ozone in human urine and we suspect that the ozone level would have to be very high, probably dangerously so, for that to be the case. [Queries for citations for this point are pending - [11] - Ed.]
Questions & Answers regarding this article
Questions & answers about dangers or hazards when using ozone generators for mold or odor reduction in buildings, boats, cars, campers, trucks.
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[6]Ozone
is not a substitute for mold removal and its reaction with building materials,
but applied by an expert may help deodorize, a cleaning article by Jim Holland -
http://www.icsmag.com/CDA/ArticleInformation/features/BNP__Features__Item/0,3035,118663,00.html
[7] Ozone as an oxidant, a few references from the Canadian Government
Bogaty,
H., Campbell K. S., and Appel, W. D. (1952). The oxidation of cellulose by ozone in small
concentrations. Text. Res. J. 22: 81-83.
Bradley,
C. E., and Haagen-Smit, A. J. (1951). The application of rubber in the
quantitative determination of ozone. Rubber Chem. Technol. 24: 750-755.
Cass, G. R., Nazaroff, W. W., Tiller, C., and Whitmore, P. M. (1991). Protection of
works of art from damage due to atmospheric ozone. Atmospheric Environment,
25A( 2): 441-451.
Druzik, J. R. (1985). Ozone: The Intractable Problem. We stern Association for Art
Conservation newsletter. Http://sul-server-2.stanford.edu/waac/wn/wn07/wn07-3/wn07-302.html
(vol.7, no. 3)
[8] "Health Hazards of some Gases" Jack E. Peterson, P.E., CIH, Ph.D., May, 1987
Ozone Gas Hazards Description in our article
"Effects of Toxic Gas Exposure to Ammonia, Arsine Arsenic Bromine Carbon Dioxide Carbon Monoxide Hydride Ozone & others"
[10] "Laundry Ozone FAQ", Water Energy Laundry Consulting, 9741 Tappenbeck, Suite 1000, Houston, TX 77055 Tel: (713) 464-2580; web search 12/17/11, original source laundryconsulting.com/solution/
benefits-of-ozone-laundry/ozone-laundry-faq/
[11] "Ozone acting on human blood yields a hormetic dose-response relationship", Velio A Bocci, Iacopo Zanardi,& Valter Travagli, J Transl Med. 2011; 9: 66. Published online 2011 May 17. doi: 10.1186/1479-5876-9-66 - Quoting the article abstract:
The aim of this paper is to analyze why ozone can be medically useful when it dissolves in blood or in other biological fluids. In reviewing a number of clinical studies performed in Peripheral Arterial Diseases (PAD) during the last decades, it has been possible to confirm the long-held view that the inverted U-shaped curve, typical of the hormesis concept, is suitable to represent the therapeutic activity exerted by the so-called ozonated autohemotherapy. The quantitative and qualitative aspects of human blood ozonation have been also critically reviewed in regard to the biological, therapeutic and safety of ozone. It is hoped that this gas, although toxic for the pulmonary system during prolonged inhalation, will be soon recognized as a useful agent in oxidative-stress related diseases, joining other medical gases recently thought to be of therapeutic importance. Finally, the elucidation of the mechanisms of action of ozone as well as the obtained results in PAD may encourage clinical scientists to evaluate ozone therapy in vascular diseases in comparison to the current therapies.
[12] Petras T, Siems W, Grune T. 4-Hydroxynonenal is degraded to mercapturic acid conjugate in rat kidney. Free Radic Biol Med. 1995;19(5):685–688. doi: 10.1016/0891-5849(95)00060-B
GAS EXPOSURE EFFECTS, TOXIC Toxic Gas Exposure effects, including links
to toxic gas exposure screening and gas testing protocols.
A Toxic Gas Testing Plan: A Gas Sampling Plan for Residential and Commercial Buildings lists some of the toxic indoor gases for which we test, depending on the building complaint and building conditions
Gas Exposure Hazard Levels: for Toxic Gas Exposure to Ammonia, Arsine, Arsenic, Bromine, Carbon Dioxide, Carbon Monoxide, Hydride, Ozone - allowable exposure levels and hazard levels
"Health Hazards of Ozone-generating Air Cleaning Devices", State of California-Health and Welfare Agency, Department of Health Services,
Indoor Air Quality Section § Jed Waldman, Ph.D., Chief, Environmental Health Laboratory Branch, 850 Marina Bay Parkway, Richmond, CA 94804, 510-620-2874 § FAX: 916-440-4440
Web Search 07/29/2010 original source: http://www.cal-iaq.org/o3_fact.htm
Ozone Warnings - Use of Ozone as a "mold" remedy is ineffective and may be dangerous.
Sampling for gases in air such as VOC's, MVOC's, toxic chemicals, and combustion products.
Unfortunately no single test or tool can detect all possible building contaminants. We use methods and equipment which can test for common
contaminants. If the identity of a specific contaminant is known in advance we can also test for a very large number of specific contaminant
gases in buildings.
We use gas sampling equipment provided by the two most reliable companies
in the world, Draeger-Safety's detector-tubes and Drager accuro bellows pump, the Gastec cylinder pump
and detector-tube system produced by Gastec or Sensidyne, and
we also use Sensidyne's Gilian air pump. For broad screening for combustibles and a number of other
toxic gases and for leak tracing we also use Amprobe's Tif8850. All of these instruments, their applications, and sensitivities (minimum detectable limits) for specific
gases are described in our Gas Sampling Plan online document.
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
US EPA - Mold Remediation in Schools and Commercial Building [Copy on file at /sickhouse/EPA_Mold_Remediation_in_Schools.pdf ] - US EPA
US EPA - Una Breva Guia a Moho - Hongo [Copy on file as /sickhouse/EPA_Moho_Guia_sp.pdf - en Espanol
Allergies, Allergens, Allergy Testing in Buildings - References & Products
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) - The Atlas of Clinical Fungi is also available on CD ROM
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.
Ozone Warnings - Use of Ozone as a "mold" remedy is ineffective and may be dangerous.
Rot concerns in buildings-some building mold such as Meruliporia incrassata "Poria" risks serious rot and hidden structural damage
US EPA: Una Breva Guia a Moho - Hongo [Copy on file as /sickhouse/EPA_Moho_Guia_sp.pdf - en Espanol
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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