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About Ozone

Ozone, or O3, is simply a supercharged form of oxygen. We refer to the regular oxygen molecule that we breathe as O2. Ozone is essentially O2 with an extra oxygen atom attached. Thus it carries the O3 designation. Oxygen is regularly transformed into ozone through forces such as lightning, and also ultra-violet (UV) light from the sun striking the atmosphere of the earth. Nature has been creating O3 for millions of years as a natural sanitizer. After a short period of time the O3 molecule is designed to revert back to O2, regular oxygen, leaving no residue.

How We Learn About It

The general public learns about ozone in two different ways. The first is the protective ozone layer in the upper atmosphere that helps to reduce the amount of ultra-violet light that strikes the earth, keeping our planet cooler. This natural layer of O3 has gradually been depleted as a result of specific pollutants such as aerosols and the older refrigerant gases.

This depletion is sometimes referred to as “holes in the ozone layer” and is also a contributor to skin cancer because too much UV light is now getting through. Steps have been taken over the past 20 years by governments to reduce these pollutants and there are hopeful signs that the ozone layer is making a slow comeback.

The second way we learn about O3 is the ground level ozone that develops in polluted cities. Automobiles and industry pollute the air through exhaust emissions. When ultra-violet (UV) light from the sun strikes these emissions, ozone is created as one of the byproducts. Burning fossil fuel creates many other pollutants as well, but ozone is the easy to measure and used as an overall indicator of the pollution.

Since life began, nature has created ozone by sunlight striking gases emitted from decaying matter as a way to keep the earth fresh and clean. This is nature’s response to pollution in the air. When the exhaust emissions are high, the O3 levels become high as a response to the excessive pollutants that are emitted, especially during summer. The ozone levels generally rise during the day in response to the greater amount of sunshine and go back down at night as the O3 breaks down to O2. Ongoing exposure to high levels of ozone at ground level can cause respiratory irritation, especially when combined with particulate and the many other gases emitted from burning fuels.

So there is concern about not enough ozone in the upper atmosphere to protect us, as well as elevated amounts at ground level in some cities that may cause irritation, both in response to pollution. These two ozone issues are sometimes confused with the main concern about burning fossil fuels, which is the release of chemicals such as carbon dioxide. These pollutants are known as “greenhouse gases” that trap heat coming off the earth and prevent it from escaping out into space. Carbon dioxide is the main contributor to global warming, and very much on the rise with no overall solution on the horizon. The protective ozone layer, on the other hand, appears to be returning as a result of coordinated governmental actions. We can only hope that carbon levels will also come into balance at some point in the future through conservation, technology and cooperative governmental policies.

Without O3 and UV light the earth would be a very smelly place with mold, mildew and viruses running rampant. These natural sanitizers work together and are designed to keep the outdoors fresh, clean and healthy. Normally, however, there is very little ozone or UV light that gets into our indoor spaces where we spend nearly all of our time. This is because the buildings where we live and work are designed to shut out the natural elements. As a result, organic matter, moisture, chemicals, microorganisms and other elements combine to generate unhealthy indoor odors.

How It Is Used

Today, ozone is intentionally produced by man for a variety of purification purposes. It is created by corona discharge as an electrical current is sent to a dielectric material such as a ceramic plate, which splits the O2 molecule creating O3. Ozone can also be created using a UV lamp that emits light in a certain spectrum in order to split the O2 molecule. The main use of ozone is for cleaning and disinfecting.

Ozone is injected in nearly all bottled waters and is widely used in Europe for treating municipal water supplies. It is a great alternative to chlorine for water purification, although more expensive, because it leaves no taste or chemical residue. Sewage and other waste are sometimes treated with ozone because it leaves no residue. O3 is also used for indoor air treatment but care must be taken so that is both safe and effective.

The typical way O3 is used commercially for air treatment is by generating ozone in an unoccupied space. For example, if a hotel wants to change a smoking room to a non-smoking room, they often use a commercial ozone generator like the OdorFree to pull odors out of the carpet, drapes, bedding, etc. Smoke and fire damage restoration service companies also use O3 to remove residual odors.

The FDA has approved O3 for treatment of air and water in food processing plants because it reduces microorganism counts without impacting the flavor. Flood and water damage restoration companies sometimes treat air with O3 at high levels in unoccupied spaces to get rid of musty smells as well as mold and mildew. Restaurants, bars, casinos, cruise ships, rental apartments, schools, offices, time shares and many other locations are beginning to treat their facilities with ozone during the off hours to get rid of odors and keep the property smelling fresh and clean.

The reason that ozone is able to reduce strong odors is because it goes after pollutants at the source. O3 is a very active form of oxygen that will naturally circulate throughout the room oxidizing odors on surfaces. Ozone can also follow the same path that vapors took when they entered soft materials and oxidize many of those embedded odors. It can help accelerate the dissipation of chemicals from new carpet, furniture and paint as well. There are numerous other applications.


The level of O3 generated in a particular setting on the dial will vary with humidity, altitude, household contents, level of indoor pollutants and other factors. The average person is able to smell ozone as the room level approaches 30 part per billion (ppb) indoors. The FDA sets an upper level of 50 ppb in continuously occupied spaces for sensitive persons such as the very young, the elderly and the sick. The EPA has set a target level of 80 ppb for outside air in cities, but that level is regularly exceeded.

The properties that make ozone a powerful cleaner and disinfectant also create a concern for long-term exposure. Excessive ozone concentrations can cause mucus membrane or respiratory irritation. But in order to successfully eliminate heavy odors or reduce microorganism growth, the levels may need to be elevated. Therefore, it is best to use ozone for air treatment in unoccupied spaces. If O3 is detected when entering a room, it is important to turn the ozone generator off, and vacate the area until it dissipates. This usually takes about an hour.

An Ongoing Cycle

Ozone is an important factor in protecting the earth from too much sunlight coming through the upper atmosphere, while also helping keep it fresh and clean at ground level. In the upper atmosphere and at ground level O3 is created daily, as it has for eons, and then reverts back to O2 again. This is called the oxygen-ozone cycle. At ground level, O3 normally reverts back to O2 in about an hour after it has been created. O3 naturally has a clean, sanitizing smell somewhat similar to chlorine. The difference with ozone is that the sanitizing smell quickly dissipates after the odors have been eliminated, as the O3 reverts back to oxygen. The end result is that an area treated with ozone becomes free of odors, as nature intended.

The Odor Answer Line 1-800-683-9749 Call us for any questions you may have on how to treat particular odors or which model to choose.

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We use ozone generators when a hotel room has smoke odors, and the OdorFree eliminates them in short order. The hotel staff really appreciates this particular ozone generator because it is simple to operate and so easy to maintain. I am transferring to another Hilton property in about eight weeks and will be placing another order with OdorFree to eliminate hotel room odor there.

Bill Simmons

Hilton Garden Inn

Winston-Salem, North Carolina