Photograph of  .Ozone O3 Exposure Standards, Chemical Effects of Air Cleaners on Indoor Ozone Concentration

  • OZONE EXPOSURE STANDARDS - CONTENTS: OZONE GAS O3 EXPOSURE LIMITS & Exposure Standards. Table of Ozone Gas Exposure Effects, Risk Factors, & Standards. Table of Ozone O3 Bactericidal & Sterilization Levels & Effects. 3 STEPS to ASSESS POSSIBLE HARM from OZONE GAS O3 EXPOSURE
  • POST a QUESTION or READ FAQs about exposure limits, Ozone PELS, Ozone TLVs & effects of exposure to Ozone gas

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Ozone gas exposure standards & exposure limits or PELs:

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.

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.

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Ozone O3 Gas Exposure Limits & Exposure Standards

Article Contents

Ozone is a very strong oxidizer. As it oxidizes a substance ozone will literally destroy the substance’s molecule.[15]

General ozone exposure limits - PELs & TLVs

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.

OSHA PEL™ for Ozone: TWA 0.1 ppm (0.2 mg/m3)

PEL = Permissible Exposure Limit

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 expressed by NOISH as

NIOSH REL for Ozone: C 0.10 ppm (0.2 mg/m3)

REL = Recommended Exposure Limit and "C" = Concentration

(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 (at REFERENCES) 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    

Ozone TLV

Threshold Limit Value

Threshold concentration level for Ozone

At this level or below, injury is not expected in an industrial setting over an 8-hour work-day exposure

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.

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.



The columns in this table are separate subtopics and do not cross-correlate with one another.


Ozone O3 Bactericidal & Sterilization Levels & Effects

Examples of Sterilization Effects Achieved by Ozone Processes & Exposures1
O3 Ozone Concentration Level in liquid solution  O3 Ozone Exposure Time  Bacteria / Pathogen % Sterilization Effect
10 mg /M3 20 minutes Hepatitis B Surface Antigen (HbsAg) 99.99 %
8 mg /M3 10 minutes Mycoplasma, Chlamydia 99.85%
0.5 ppm /L 5 minutes Influenza A virus 99%
4 mg /L 3 minutes HIV 100%
0.25 mg /L 1 minute Ape rotavirus SA-H & Human rotavirus type 2 99.6%
0.13 mg /l 30 seconds PVI 100%
40 ug /L 20 seconds Salva bacteria E coli ms2 98%
0.6 ppm 10 minutes S. salivarius 98% Elford et al. (1942) [15]
0.6 ppm 240 seconds S. epidermis Heindel et al. (1993) 99.4% [15]
0.4 ppm   pX174 (virus) 99.9% De Mik (1977)

Notes to the table:

1. Original source: adapted & expanded from Trump Electronics [14] Trump Electronics produces integrated ozone & water recovery systems including clothes washing machines that make use of dissolved (in water) ozone.

2. [15] Laurence Franken, M.S., "The Application of Ozone Technology for Public Health and Industry", Nov. 2005, Food Safety & Security at Kansas State University, Kansas State University, Website:, web search 10/12/12, original source:,%20Kansas%20State%20University.pdf

Note: This paper is sponsored by EcoQuest International [Copy on file as Ozone_Applications_Franken_KSU.pdf] Excerpt:

Studies conducted by Midwest Research Institute (Huebner, 2003), using 0.05 ppm also showed reductions in five different pathogens. Reductions is Escherichia coli, Staphyloccus aureus, Salmonella choleraesuis, and Penicillium chrysogenum populations were between 30% and 70%, following 6 to 24 hour exposure. Reductions of Candida albicans were even greater at 90%.

Common Applications of Ozone

Please see the Ozone applications listed at More Reading just below.


How to Assess Risk of Harm or Injury from Ozone Exposure

Reader Question: I work with ozone generators - how can I see if I have injured myself

After reading this I got very nervous since I work with ozone generators a lot. How can I see if I have already caused myself too much damage to have bad long term affects? Is there a way to get tested? - Josh 11/30/11

Reply: 3 Steps to Assessing Possible Harm from Exposure to Ozone Gas O3

Josh, by no means do we advocate panic about ozone, but rather we caution about the importance of distinguishing between long and well-established valid Ozone O3 applications whose effectiveness is accepted and well documented and other O3 applications whose effectiveness is questioned or perhaps completely refuted by experts. And we note a third category of ozone issues arising from over-dosing or over-exposing environments or people. Details are

To answer your question more specifically, that is, have you been injured by ozone exposure, a topic on which I am NOT expert, I can but suggest:

  1. Consult with your personal physician about your concerns and any complaints that s/he might think are O3 related; if that consult leads to a concern, your doctor will refer you to an appropriate specialist for interview, and examination. Ozone itself is highly volatile and while it has been detected in urine of people that's only for immediately-recent exposure; otherwise, the ozone itself is likely not to be detected but if there has been an injury, that may be diagnosed.
  2. Obtain data about your workplace (or other) exposure to O3 (ozone) including the frequency, duration, and concentration of ozone to which you were exposed, and provide that information to your physician.
  3. Compare exposure to the Ozone TLV: Take a look at our first table above, where you can read about the TLV or "Threshold Limit Value" for ozone exposure.

    For ozone, the TLV concentration is 0.1 ppm (0.1 parts per million of ozone in air). It is reasonable to conclude that as long as the ozone concentration to which you have been exposed has been maintained at or below that level, injury is not expected as long as your exposure durations coincided reasonably well with or were less than the 8 hours per day, 40 hours per week regimen.

See OZONE TESTS for methods for testing for the level of exposure to Ozone Gas


Continue reading at OZONE MOLD KILL TREATMENT or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.


Or see OZONE HAZARDS - home



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