Ozone dose or treatment time: how long should you run the ozone machine?

The answer, as we explain here, depends on the treatment area, the problem being addressed, the specific ozone generator's output, and other instructions from the manufacturer.

Ozone has been widely used as a disinfection method for more than 100 years and has applications ranging from hospital disinfection to water treatment. But if ozone treatments are not matched to the application the results can be both ineffective and potentially harmful, causing permanent chemical offgassing from oxidized building materials or even the abandonment of an ozone-treated car, camper, truck or other vehicle..

Ozone Generator Treatment Time Guidelines

Watch out: the most-basic and critical advice is that to use an ozone generating machine safely and effectively in any application such as in a building, or in a car or other vehicle, you must read and follow the manufacturer's instructions.

You will read in our ozone treatment time examples below on this page that usually when people get into trouble: building or vehicle damage from over-dozing with ozone or even individual health injury from exposure to ozone, it's because those instructions were misunderstood or ignored.

There is no single correct "ozone dose" or safe output level or safe exposure or treatment time that will be right for all circumstances.

Instead, the proper ozone treatment time or "dose" depends on a number of factors including the following:

• on the level of ozone output from the specific ozone generating equipment - and those vary all over the place so right there we see there's no one "right answer"
• on the number of ozone generators being run at once in the building
• the location of the ozone generator
• the volume of the space into which ozone is being pumped
• the level of fresh air ventilation intake and exhaust rates, and amount of air circulation in the treatment space
• more-subtle factors like the temperature and relative humidity of the treatment space
• occupants: and of course no living beings, pets, etc. should be present in the treatment area at all - so in that case, ANY duration time of operation is too ling if that advice isn't followed.
• what materials are present in the treatment space and how vulnerable are they to oxidation by the ozone gas
• the ozone generator's specific instructions

Watch out: most instructions for ozone generators will state

Never use the product when humans or pets are around.

Exposed to high concentration of ozone will be harmful. Make sure all ozone is reverted back to oxygen before you enter the space, which takes approximately 30 minutes.

At OZONE HAZARDS & OZONE TOXICITY LEVELS we warn that exposure to 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. ]Health hazards to humans and animals occur and can be severe at ozone levels used for indoor cleaning purposes.

Details about the toxicity of ozone are found

at OZONE TOXICITY

Also at OZONE SHOCK TREATMENTS NOT RECOMMENDED we include these warnings:

Watch out:  Ozone is a highly toxic, oxidizing gas. It can be absorbed into the body via inhalation, skin or the eyes. It can also oxidize building materials. See the Ozone hazard and use warning articles listed at the end of this article.

Watch out: In-Home or "portable" ozone generators and industrial or "shock treatment" ozone generators not only fail to find and remove the source of mold or building odors, in addition ozone concentrations generated by ionic air purifiers can exceed (industrial) levels permitted by U.S. Environmental Protection Agency.

See also

• HEALTH HAZARDS of Ozone-generating Air Cleaning Devices", [PDF] State of California-Health and Welfare Agency, Department of Health Services, Indoor Air Quality Section
  

On 2022-05-24 by InspectApedia-911 (mod) - I fell for the Ozone myth to get rid of some mold in my fairly new truck

@Tristan,

We have already included in our articles some resource citations of research on the subject but I will look further to see what I can add.

See OZONE REFERENCES at https://inspectapedia.com/sickhouse/Ozone_References.php

Where are we cite some of the extensive research that has been done about the proper and improper use of ozone treatments as well as potential health hazards.

On 2022-05-24 by Tristan

I recently fell for the Ozone myth to get rid of some mold in my fairly new truck. A company was suggested by my car detailer and my truck was ozoned twice, the second time being an hour or two of concentrated ozone. The off gassing wasn't immediately that noticeable but progressively got worse to the point I couldn't drive it.

The funny thing is I thought it was still the mold but had changed smells from the treatment (Sounds dumb to me now too). The mold caused that musty smell and now after the treatment it is a chemical and somewhat sweet smell.

What I am looking for is for some solid studies or other references to back up my claim to the company/their insurance/lawyer. I am pretty sure they will deny they caused this and I want to go in ready to fight them on this. It's possible my truck is a write off as I get sick driving it even with the windows fully down.

Thanks for the helpful resources already!

Continuing with an excerpt from a more-helpful ozone generator manual we have

(B5) OZONE APPLICATION: RUN TIMES

Please see the addendum to this manual that gives our recommended run times based on several factors including the degree of odor, size of the treatment space, and model type for your specific MaxBlaster ozone generator.

All projects are unique and there is no way we can accurately predict the exact run time to accomplish your specific goal. Much of your success will be determined by your ability to analyze the results after each cycle then adjust your protocol throughout the entire project.

Running your ozone machine for too long at one time may cause adverse results. For example just because we recommend running your MaxBlaster for 8 hours at one time for good results in a specific project does not mean that running it for 80 hours at one time will yield great results.

In fact just the opposite may become true. If you run the high-output ozone machine for too long you may create an adverse reaction leading to a new odor problem all together.

For this reason we demand that our machines not exceed 8 hours of continuous run time for any project. See (B8) ‘Rinse & Repeat Pattern’.

- source: MAXBLASTER OZONE GENERATOR MANUAL [PDF] MaxBlaster USA Phone: 800-575-1787 186 Lear Road Avon Lake, Ohio 44012 USA - retrieved 2022/04/06 original source: http://www.maxblasterusa.com/INSTRUCTIONS.html

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

On 2022-04-06 by Inspectapedia Com Moderator (mod) - "an hour of ozone treatment is harmless" ? Really?

@David,

I don't quite agree that categorically "an hour of ozone treatment is harmless"

Health experts and environmental experts and similar folks like to say "the dose makes the poison".

How long is a safe time to run an ozone generator in a building

So the answer to your perfectly-reasonable question of just how long is too long for ozone treatment? is

... as my Tampa friend Mark Cramer says,

It depends on the ozone treatment time factors we list at the beginning of this article.

So what's the right thing to do?

Start by reading the instructions from the ozone generator machine's manufacturer. That company has a vested interest in the successful use of their product.

They've got to give the user advice about location and duration of treatment as a function of at the very least, the cubic feet or meters of the treatment space.

The Recommended Articles list at Recommended Articles give more information that fills in some of this with examples, case histories, and references.

Examples of Ozone Generator Run Time Instructions

The instructions for an Airthereal ozone generator we sampled - just as a random example - specified

Ozone Production 10000mg/h
Air Flow Volume 120CFM
Timer 0-120 minutes

So the manufacturer starts with a nice clue: you can not run that specific machine for more than two hours without taking a break of at least half an hour and then human intervention.

Yet we see some companies advising that you need to ozone a whole house for at least 3-10 hours and for as much as 25-30 hours "to eliminate most pollutants" - maybe so or maybe that's an enormous overdose - DEPENDING - on the variables that I listed above.

Here's another example for a different ozone generator:

Ozone Output 600 mg/hour, no other data on airflow, cfm, etc.

That manufacturer's ozone generator controls specify run intervals like these:

• 1 Run 2 minutes and turn off , one time run only
  
• 2 Run 5 minutes and turn off, one time run only
  
• 3 Run 10 minutes and turn off, one time run only
  
• 4 Run 15 minutes and turn off, one time run only
  
• 5 Run 20 minutes and turn off, one time run only
  
• 6 Operates for 2 minutes every hour, repeats every hour
  
• 7 Operates for 5 minutes every hour, repeats every hour
  
• 8 Operates for 10 minutes every hour, repeats every hour
  
• 9 Operates for 15 minutes every hour, repeats every hour
  
• 10 Operates for 20 minutes every hour, repeats every hour
  
• 11 Operates for 2 minutes every four hours, repeats every 4 hours
  
• 12 Operates for 5 minutes every four hours, repeats every 4 hours
  
• 13 Operates for 10 minutes every four hours, repeats every 4 hours
  
• 14 Operates for 20 minutes every four hours, repeats every 4 hours
  
• 15 Operates for 30 minutes every four hours, repeats every 4 hours

You can see that's a heck of a lot less than 25-30 hours!

It was interesting that the Ozone generator instructions we read didn't mention the dangers of running the equipment too long nor was there any "maximum run time" in the instructions, perhaps in part because the manufacturer too knows of the very widely varying circumstances and conditions such as those ozone dose parameters I listed above.

So perhaps you'll agree there is no single right answer to how long is a safe time to run an ozone generator in a building? without risking the hazards listed in this article series.

Supporting Research: Ozone Treatment Duration & Strength

• California DHS, HEALTH HAZARDS OF OZONE-GENERATING AIR CLEANING DEVICES [PDF] 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 MSDS, provided by OREC™ Ozone Research Equipment Company, a subsidiary of CCSi, Inc., 221 Beaver Street, Akron, Ohio 44304 Telephone: 800.742.8535 / 330.376.3600
• Ozone exposure limits: NIOSH REL: C 0.1 ppm (0.2 mg/m³); OSHA PEL: TWA 0.1 ppm (0.2 mg/m³)
• Indoor air, https://www.health.ny.gov/environmental/air_quality/#indoor_air New York State Department of Health
• 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. (vol.7, no. 3)
• "Health Hazards of some Gases" Jack E. Peterson, P.E., CIH, Ph.D., May, 1987

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2022-04-06 by David - how long ozone generator machine time is "too long" ?

how long is too long?

Obviously an hour wont really cause damage to the materials but what's too long? 4 hours? 12 hours? 24 hours? What's a safe duration to prevent damaging household materials?

On 2021-02-23 - by (mod) - house smells of worse chemicals after using an ozone generator for 18 hours at 11,000 mg/h.

@James,

I'm sorry to report that in most cases that I have examined myself as well as those reported by our readers, once the material has been oxidized it will continue to email orders unless

Either the material can be coated with a sealant or the material or item is disposed-of.

Classic examples are oxidized carpet padding or couch upholstery that continue to smell until those items are removed from the building.

Try ventilating with fresh air and also try pinpointing the odor souuce using

the SMELL PATCH TEST to FIND ODOR SOURCE

Either the material can be coated with a sealant or the material or item is disposed of. Classic examples are oxidized carpet padding or couch upholstery that continue to smell until those items are removed from the building.

Try ventilating with fresh air and also try pinpointing the odor source using the SMELL PATCH TEST KIT that we describe in these articles

On 2021-02-21 by James - this ozone generator produces 11,000 mg/h.

Following up from previous post, it was a unit that produces 11,000 mg/h.

I ran and ozone generator I bought for about 18 hours in a four-bedroom house with no fan to circulate the air.

After airing out for a couple hours with open windows in a fan, it still smells of chemicals, and I realize it's probably off-gassing from things like the couch. Both my wife and I got headaches after being inside today.

If I have oxidized my couch or other things inside, will they eventually stop off gassing or is everything oxidized permanently ruined?

On 2021-01-05 - by (mod) -

Raven, thank you for a helpful criticism and suggestion about ozone generator usage or safe "run times" in buildings.

Please find your question and my detailed reply at OZONE TREATMENT TIME RECOMMENDATIONS - now found above on this page.

We welcome your further questions or suggestions.

You may need to clear or refresh your browser cache to see the updated page. We welcome your further photos, comments, questions.

On 2021-01-05 by Raven

You specifically state that only INCORRECT use of the Ozone will cause the bad effect.

You NEVER state the correct amount of time to ensure the house is 100% safe for people with MCS.

Or any other specifications that are necessary to ensure that the Ozone machine is made correctly. You also continuously refer to "mold" or "skunk" odor, but for some reason never mention the most obvious reason that Ozone is requires, cigarettes or Downy or etc.

On 2014-03-06 - by (mod) - for how long the ozone generator must be used while driving a car?

Deepak,

Watch out: in no case would you be inside of a vehicle nor a room in a building where an ozone generator is in use. Doing so risks rapid and serious injury to your lungs and possibly other medical complications.

Having issued the warnings about ozone generators in this article and others of the series, and realizing that generating ozone in a small, enclosed and occupied space would be particularly dangerous, and with no information about what ozone generator you are considering, I'm afraid to venture an answer to your question.

I will warn that if you smell ozone the level of exposure is most likely unsafe.

On 2014-03-06 by deepak

for how long the ozone generator must be used while driving a car?

On 2019-12-09 - by (mod) - safe to run an ozone machine for 1 hour then move it and run it again for an hour?

Beware that as you will read in these articles, overdosing with ozone can cause far more trouble than the problem you set out to treat in the first place.

I can't guess at what's a safe usage level - there are too many unknowns about the building areas, volumes, materials and ozone generation rate;

Typically it's carpet and carpet padding, finishes on surfaces, plastics and the like that are most-likely to be oxidized and damaged;

I would not try ozone for the problem you describe without some supporting research.

But I might require the contractor to paint the smelly surfaces with a sealant such as those used to control odors after a fire.

On 2019-12-04 by Bernadine Young

I have a 50 yr warranty OSB subfloor product put down new in the main part of my house that is under major renovations (1400 sq ft, 14 ft at peak of vaulted ceilings) and plan to run an ozone machine (Airthereal 10,000 mg/h) because the drywall guys used at least 30 oz of cheap degreasing detergent mixed into each bucket of all purpose joint compound, believing the more they use the smoother it goes on, but the smell is awful, strong perfume and chemical smell, even though now it is dried.

I stopped the job, want to run the ozone machine and then they can put final coat of mud on, but worried about the new subflooring, bare sheetrock and mini-split systems I have covered in light plastic.

Do you think it will be safe to run the ozone machine for an hr at one end, wait an hour, then an hour at the other end of the space with lots of doors and some upper opening in walls between some of the rooms -- any advice about the pros and cons of my plan under these circumstances, and idea what might be damaged?

...

Continue reading at OZONE SHOCK TREATMENTS NOT RECOMMENDED or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• MOLD CLEANUP - MISTAKES to AVOID
• ODORS, SMELLS, GASES IN BUILDINGS-DIAGNOSIS & CURE
• OZONE HAZARDS - home
  • OZONE AIR PURIFIER WARNINGS
  • OZONE EXPOSURE STANDARDS
  • OZONE GAS EXPOSURE EFFECTS
  • OZONE GAS EXPOSURE LIMITS - EPA
  • OZONE GENERATOR EFFECTIVENESS for INDOOR AIR POLLUTION
  • OZONE HAZARDS
  • OZONE in HOT TUBS, SPAS, POOLS
  • OZONE MOLD / ODOR TREATMENT WARNINGS
  • OZONE MSDS [PDF]
  • OZONE REFERENCES & OZONE GENERATOR INSTRUCTIONS
  • OZONE SHOCK TREATMENTS NOT RECOMMENDED
  • OZONE TREATMENT TIME RECOMMENDATIONS
  • OZONE TESTS
  • OZONE TOXICITY
  • RELYING on OZONE to KILL MOLD
  • XENON LAMP OZONE OUTPUT?
• SMELL PATCH TEST to FIND ODOR SOURCE

Suggested citation for this web page

OZONE TREATMENT TIME RECOMMENDATIONS at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to BUILDING ODOR DIAGNOSIS & CURE

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