OZONE TOXICITY - CONTENTS: Ozone Toxicity Levels: How toxic is ozone, general background, levels of ozone gas toxicity, ozone gas applications. Is an indoor ozone generator harmful to family or pets? Properties and Actual Ozone Output of the OZN-jr ozone generator. What is the Legal Definition of "Up To" in Advertising Claims? What is the toxicity of Ozone Gas?
InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.
Toxicity of ozone gas:
This article discusses the toxicity of ozone gas in buildings, providing a summary of the hazards of indoor ozone levels & indoor ozone generators as well as the use of ozone generators for "mold remediation" - a popular but quite doubtful mold remedy. 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.
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.
Reader Question: Is an indoor ozone generator harmful to family or pets?
Anonymous asked: A friend of ours gave us a ozone junior to use in our home it comes on for 10 minutes off for 10 minutes. We are happy with it as far as taking care of the pet odors or any odors but are concerned on whether it is safe to use as it had no paper work. I would just like to know whether this can be harmful to my family or pets? - N.A.
(Feb 17, 2015) Derik said:
Please evaluate the claims by Forever Ozone also selling on Amazon: 7000mg/hour (7g/hr). They use a 100 sq ft room.
Reply: It depends ...
It might be. A competent onsite inspection or testing by an expert might find other unsafe conditions in your home or conditions that are affecting how your ozone air machine performs. That said, here are some things to consider:
Start by making sure you are using the equipment according to the manufacturer's instructions.
Beginning just below, we discuss actual ozone gas toxicity - harmful levels. Also s
ee OZONE MSDS.
Also you can read about the actual OZONE EXPOSURE STANDARDS but without expert testing in your own home you may have no idea how your home's ozone level compares with the standards.
Our opinion is that as a very crude rule of thumb, if you smell ozone or the air has a funny "electric" smell, that is if there is a detectable ozone odor, the equipment is probably not operating safely or correctly.
Other than that crude measure, you'd have to either rely on the manufacture's quality control and on following the product instructions, or you'd need to make actual ozone level measurements in the building where the equipment is used. We measure ozone gas levels (when we are convinced there is a reason to do so) using a gas measurement pump and tube system such as that described
at USE of a DRAGER GAS TESTING PUMP.
Properties and Actual Ozone Output of the OZN-jr ozone generator
Reader Questions about ozone generators & their output:
Derik & Anon: here is an example calculation in which we show how you can calculate the cubic feet in a room and the ozone output of an ozone generator to obtain the actual ozone concentration in that space, assuming that the space is closed and air-tight. Certainly with doors or windows open or drafts the effects of the ozone generator will be different (and probably reduced).
Information about your "ozone junior" ozone generator: IF you are referring to the OZN-jr Ozone Generator that we noted is for sale at Amazon.com. An Amazon advertisement viewed in March 2011 indicated that the OZN-jr ozone generator unit produces 200 mg of ozone per hour. The advertising material asserts that the product is "good for deodorizing up to 1000 cubic feet."
How big is a 1000 cubic foot room? Figuring an 8-foot ceiling, that's about 125 square feet, or a 10 x 12 room.
Calculating ozone generator output concentration in a room: How much is 200 mg of ozone per hour seen in the [March 2011] Amazon Ad? We don't know because the 200 mg number looks incomplete. If that 200 mg of ozone is being produced over an hour in a 1000 cubic foot room, that would be a very low concentration of ozone. 1000 cubic feet = 23,317 liters. 200 mg of something distributed into 23,317 liters amounts to about 0.0085 mg per liter or about 0.0085 ppm. In other words, almost nothing.
How much is 8 mg/hour ozone output seen at the OZN-jr product web page [March 2011]? Following the calculation above, output is 0.0003 ppm - almost less than nothing.
In our OPINION, at those ozone output levels your machine would not be hurting anyone, but it also would not be doing much that you'll notice either. Our detailed text below states that " ... the odor of ozone can be detected and identified by most people at a concentration of from 0.02 to 0.05 ppm (parts ozone per million parts air + ozone)."
Watch out: there is a very wide range of ozone output from different types of ozone generating equipment, and some equipment can be used at output settings or in enclosed environments to produce levels of ozone gas dangerous to occupants and damaging to building contents.
What is the Legal Definition of "Up To" in Advertising Claims
With an advertising attorney we recently discussed the legal requirements for advertisers who make "up to" claims. She informs us that in the U.S. law on "up to" claims requires that the product meet the "up to" claim at least ten percent of the time. Translating this into plain language, in a given installation the OZN-jr can meet its advertising claims if in ten percent of cases it deodorizes 1000 cubic feet (that's a room that is about 8 feet by 15.6 feet or 125 square feet if the ceiling height is also 8 feet). And 90 percent of the time it can perform less well, or even not at all.
The ability to deodorize a space using just about any deodorizing method (other than complete removal of the odor source) depends on other variables that are certainly not under the product manufacturer's control, such as the level of odor or smell in the first place, the persistence and nature of the odor source, building air movement properties, space size, equipment location, and lots more.
Toxicity of Ozone Gas
The following information about Ozone is quoted from "Health
Hazards of Some Gases" with minor edits and additions. See REFERENCES 
is a kind (called an "allotrope") of oxygen . It is formed in the
ionosphere by the action of ultraviolet radiation from sunlight on oxygen.
Lightning strokes are another natural source of ozone and the characteristic
odor of that material can often be noted during and after a thunderstorm.
pollutants are emitted into the air either by man or nature, almost all are
eventually removed by one or more of several processes including reaction under
the influence of ultraviolet radiation. One series of such reactions results in
the formation of ozone as a "secondary" (formed by reaction in the
air) air pollutant, often in rather high concentrations (several tenths of a
part per million).
ozone can be formed by nature's sparks (lightning), it can also be formed by
man's. Whenever an electrical spark or corona occurs in air, some ozone is
formed. This accounts for the characteristic odor noted near an operating
electric motor such as an electric shaver.
ozone is found in so many places, its toxicity (ability to injure a living
organism by other than mechanical means) has been investigated extensively
since the early 1900s. Experimentation has shown that the odor of ozone can be
detected and identified by most people at a concentration of from 0.02 to 0.05
ppm (parts ozone per million parts air + ozone). As the concentration increases
to a few tenths of a part per million, the first effect noted is likely to be a
feeling of dryness in the back of the throat. If a concentration on the order
of 0.2 or 0.3 ppm is inhaled more or less continuously for several hours to a
few days some lung irritation may result.
concentrations can produce several kinds of toxic effects if exposures are
sufficiently prolonged. Eye irritation (despite newspaper and TV accounts
seemingly indicating otherwise) occurs only at concentrations high enough to
result in other, more severe, toxic effects.
is a very reactive substance. It will readily react with just about any material
capable of being oxidized, and with many that are not. The material with which
it reacts may be a gas or vapor, a particle floating in the air (a mold spore,
for example), or a solid (or liquid) surface. For this reason, when ozone is
present in most enclosed spaces its concentration declines quite rapidly with
time. Of course, if ozone is being generated more rapidly than it is destroyed
by reaction, its concentration can build up. This is the main reason why
devices that produce relatively large amounts of ozone are safe only in
relatively large enclosures and why the ozone generation rate should be reduced
in small enclosures.
is well known for its ability to eliminate certain odors. How this is
accomplished is controversial. At concentrations just above the odor threshold,
some odors do seem to vanish. The main reason for this may be ozone's ability
to desensitize the olfactory apparatus so that the odors can no longer be
perceived. Some evidence indicates that this may be the case at least occasionally.
Other evidence indicates that ozone may react with the odor-causing substances,
eliminating them from the air (this is probably the only mechanism that
operates when concentrations are below the odor threshold).
some people have insisted that even if ozone does not paralyze the olfactory
sense, its odor is such that it "masks" other odors. Perhaps all
three mechanisms operate, each in its own area of effectiveness.
with all other materials, ozone has a dose-effect relationship with a
threshold. That is, once the threshold dose has been exceeded, toxic effects
are proportional to dose. For inhaled gases, dose is proportional to both time
and concentration. If the duration of exposures cannot be controlled (as is
usually the case), then the concentration must be kept low enough so that no
injury will occur even from prolonged and repeated exposures.
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" level
is accepted by the American Conference of Governmental Industrial Hygienists
(and is called the Threshold Limit Value by that organization) and by the
Occupational Safety and Health Administration, OSHA.
The TLV or OSHA's
Permissible Exposure Level (PEL) is not a fine line between safe and non-safe.
Instead, it represents the best judgment of a group of experts of the highest
concentration that can be inhaled repeatedly by a population of workers with no
resulting injury. Higher concentrations may or may not have any particular
effect on a specific individual.
"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."
The following questions & answers posted originally at the end of this article
Question: ozone generator to get rid of cigarette smoke odors caused new problems
2017/07/01 Sherry said:
I am purchasing a home that smelled cigarette smoke. The seller's friend has an ozone generator that was brought in on a Saturday. I entered the house on Thursday and had chest pains, dizziness and burning on my skin. The house was aired out but still has the smell.
I am now afraid to purchase this home and now worry about the effects it may have on my health. Any feedback would be appreciated
Cigarette smoke odors are tough to eliminate without a combination of cleaning of all surfaces and perhaps removal of carpeting or heavy upholstered items.
An ozone generator used as you described not only did not help, it made problems worse by oxidizing some materials in the home.
Odors resulting from an over-dose of ozone during a mis-use of an ozone generator to attack cigarette smoke odors are a second layer of trouble.
These problems can be fixed; the remedies for both odor sources (cigarette smoke and ozone-generator overdosing) are about the same.
You'll need to track down the smell source and remove, clean, or seal it.
Following a thorough cleaning of walls and ceilings and hard-surfaced floors the walls and ceilings may need to be sealed and then painted using an odor-control procedure the same as is used following a building fire.
Carpets get tossed out; drapes can be professionally cleaned.
Try the search box below or CONTACT US by email if you cannot find the answer you need at InspectApedia.
Ask a Question or Search InspectApedia
Questions & answers or comments about the toxicity of ozone gas in buildings or other enclosed spaces.
Use the "Click to Show or Hide FAQs" link just above to see recently-posted questions, comments, replies, try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.
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 -
 Ozone as an oxidant, a few references from the Canadian Government
H., Campbell K. S., and Appel, W. D. (1952). The oxidation of cellulose by ozone in small
concentrations. Text. Res. J. 22: 81-83.
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)
OZN-jr Ozone Generator, Sunlight Solutions, LLC., 2045 Niagara Falls Blvd. Suite 13 & 14, Niagara Falls, NY 14304 USA, Tel: 888-476-9269 - see
 Ozone Gas Hazards Description in our article
"Effects of Toxic Gas Exposure to Ammonia, Arsine Arsenic Bromine Carbon Dioxide Carbon Monoxide Hydride Ozone & others"
 "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/
 "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.
 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
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.
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
"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
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)
"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 in Home Vegetable Gardens,"
Department of Plant Microbiology and Pathology,
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.
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: email@example.com. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides extensive home inspection education and report writing material.
The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors. Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
TECHNICAL REFERENCE GUIDE to manufacturer's model and serial number information for heating and cooling equipment, useful for determining the age of heating boilers, furnaces, water heaters is provided by Carson Dunlop, Associates, Toronto - Carson Dunlop Weldon & Associates Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume.
Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on these courses: Enter INSPECTAHITP in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
The Horizon Software System manages business operations,scheduling, & inspection report writing using Carson Dunlop's knowledge base & color images. The Horizon system runs on always-available cloud-based software for office computers, laptops, tablets, iPad, Android, & other smartphones