This article explains the question: are indoor ozone generators effective in controlling indoor air pollution?

For almost a century, health professionals have refuted these claims (Sawyer, et. al 1913; Salls, 1927; Boeniger, 1995; American Lung Association, 1997; Al-Ahmady, 1997).

The purpose of this document is to provide accurate information regarding the use of ozone-generating devices in indoor occupied spaces.

This information is based on the most credible scientific evidence currently available.

At OZONE AIR PURIFIER WARNINGS we reported on situations in which ozone air cleaners are not recommended, we explained why ozone gas indoors can be harmful to people and other animals, and we presented some EPA information on indoor air and chemistry where ozone generators are used.

As REPORTED by the U.S. EPA, Ozone generators that are sold as air cleaners intentionally produce the gas ozone.

Often the vendors of ozone generators make statements and distribute material that lead the public to believe that these devices are always safe and effective in controlling indoor air pollution.

Are Ozone Generators Effective in Controlling Indoor Air Pollution?

The EPA says that available scientific evidence shows that at concentrations that do not exceed public health standards, ozone has little potential to remove indoor air contaminants.

Some manufacturers or vendors suggest that ozone will render almost every chemical contaminant harmless by producing a chemical reaction whose only by-products are carbon dioxide, oxygen and water. This is misleading.

• Ozone treatment time:
  
  First, a review of scientific research shows that, for many of the chemicals commonly found in indoor environments, the reaction process with ozone may take months or years (Boeniger, 1995).
  
  For all practical purposes, ozone does not react at all with such chemicals.
  
  And contrary to specific claims by some vendors, ozone generators are not effective in removing carbon monoxide (Salls, 1927; Shaughnessy et al., 1994) or formaldehyde (Esswein and Boeniger, 1994).
• Harmful ozone byproducts:
  
  Second, for many of the chemicals with which ozone does readily react, the reaction can form a variety of harmful or irritating by-products (Weschler et al., 1992a, 1992b, 1996; Zhang and Lioy, 1994).
  
  For example, in a laboratory experiment that mixed ozone with chemicals from new carpet, ozone reduced many of these chemicals, including those which can produce new carpet odor.
  
  However, in the process, the reaction produced a variety of aldehydes, and the total concentration of organic chemicals in the air increased rather than decreased after the introduction of ozone (Weschler, et. al., 1992b).
  
  In addition to aldehydes, ozone may also increase indoor concentrations of formic acid (Zhang and Lioy, 1994), both of which can irritate the lungs if produced in sufficient amounts.
  
  Some of the potential by-products produced by ozone’s reactions with other chemicals are themselves very reactive and capable of producing irritating and corrosive by-products (Weschler and Shields, 1996, 1997a, 1997b). Given the complexity of the chemical reactions that occur, additional research is needed to more completely understand the complex interactions of indoor chemicals in the presence of ozone.


• Toxic or allergenic particles removal inconsistent:
  
  Third, ozone does not remove particles (e.g., dust and pollen) from the air, including the particles that cause most allergies. However, some ozone generators are manufactured with an "ion generator" or "ionizer" in the same unit. An ionizer is a device that disperses negatively (and/or positively) charged ions into the air.
  
  These ions attach to particles in the air giving them a negative (or positive) charge so that the particles may attach to nearby surfaces such as walls or furniture, or attach to one another and settle out of the air.
  
  In recent experiments, ionizers were found to be less effective in removing particles of dust, tobacco smoke, pollen or fungal spores than either high efficiency particle filters or electrostatic precipitators. (Shaughnessy et al., 1994; Pierce, et al., 1996).
  
  However, it is apparent from other experiments that the effectiveness of particle air cleaners, including electrostatic precipitators, ion generators, or pleated filters varies widely (U.S. EPA, 1995).
• Ozone can decontaminate - what by-products are left behind? 
  
  High concentrations of ozone in air, when people are not present, are sometimes used to help decontaminate an unoccupied space from certain chemical or biological contaminants or odors (e.g., fire restoration). However, little is known about the chemical by-products left behind by these processes (Dunston and Spivak, 1997).
  
  While high concentrations of ozone in air may sometimes be appropriate in these circumstances, conditions should be sufficiently controlled to insure that no person or pet becomes exposed.
  
  Ozone can adversely affect indoor plants, and damage materials such as rubber, electrical wire coatings, and fabrics and art work containing susceptible dyes and pigments (U.S. EPA, 1996a).
• Ozone can cause new obnoxious building odors: [Not EPA data]
  
  Watch out: We add a WARNING: that use of high concentrations of ozone indoors to decontaminate or deodorize an indoor area can cause oxidation of other building materials (such as carpet padding) and may lead to the necessity of additional demolition to remove secondary and very noxious odors that result.
  
  Example cases of new noxious building odors caused by use of indoor ozone to try to get rid of odors and smells are reported at OZONE AIR PURIFIER WARNINGS
  
  and at OZONE as a "CURE" for TOXIC INDOOR MOLD or ODORS.
  
  In both cases oxidized building materials led to new noxious odors that in turn required demolition and removal of oxidized products such as carpet padding.

Can I Use Ozone Air Purifiers to Get Rid of Odors?

• In an experiment designed to produce formaldehyde concentrations representative of an embalming studio, where formaldehyde is the main odor producer, ozone showed no effect in reducing formaldehyde concentration (Esswein and Boeniger, 1994).
  
  Other experiments suggest that body odor may be masked by the smell of ozone but is not removed by ozone (Witheridge and Yaglou, 1939). Ozone is not considered useful for odor removal in building ventilation systems (ASHRAE, 1989).


• While there are few scientific studies to support the claim that ozone effectively removes odors, it is plausible that some odorous chemicals will react with ozone. For example, in some experiments, ozone appeared to react readily with certain chemicals, including some chemicals that contribute to the smell of new carpet (Weschler, 1992b; Zhang and Lioy, 1994). Ozone is also believed to react with acrolein, one of the many odorous and irritating chemicals found in secondhand tobacco smoke (US EPA, 1995).
• At OZONE TOXICITY we include calculations demonstrating the actual ozone concentration produced by a small ozone generator.

Can I Use Ozone to Prevent Mold Growth ?

• Some data suggest that low levels of ozone may reduce airborne concentrations and inhibit the growth of some biological organisms while ozone is present, but ozone concentrations would have to be 5 - 10 times higher than public health standards allow before the ozone could decontaminate the air sufficiently to prevent survival and regeneration of the organisms once the ozone is removed (Dyas, et al.,1983; Foarde et al., 1997).


• Even at high concentrations, ozone may have no effect on biological contaminants embedded in porous material such as duct lining or ceiling tiles (Foarde et al, 1997).
  
  In other words, ozone produced by ozone generators may inhibit the growth of some biological agents while it is present, but it is unlikely to fully decontaminate the air unless concentrations are high enough to be a health concern if people are present. Even with high levels of ozone, contaminants embedded in porous material may not be affected at all.

Watch out: see OZONE MOLD / ODOR TREATMENT WARNINGS

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

Reply:

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.

Our SMELL PATCH TEST to FIND ODOR SOURCE is an inexpensive way to identify the primary odor emitting surfaces or materials.

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.

See ODOR DIAGNOSIS CHECKLIST, PROCEDURE

Watch out: see OZONE MOLD / ODOR TREATMENT WARNINGS

Question: Can I sue the company who ruined my car using ozone?

(Sept 2, 2015) Rose Delalla said:

Can I sue the company who ruined my car using ozone to get rid of a car odor

Reply:

Perhaps, Rose, if the ozone generator was not properly used.

See details about the ozone-damage to a car described at CAR SMELL - Mold DEODORIZING

...

Continue reading at OZONE EXPOSURE STANDARDS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

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

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