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Claims About Ozone Therapy Don't Pass the Smell Test

While the value of ozone in water treatment and in disinfecting medical instruments has been well demonstrated, its use for medical conditions is plagued by controversy.

This article was first published in 


 in which a valet’s body odour invades a car with such ferocity that Jerry has to get rid of the vehicle because no amount of cleaning manages to eliminate the stench. Should have tried an ozone generator! Ozone is a gas with a high oxidation potential, meaning it has the ability to steal electrons from other molecules. Since electrons form chemical bonds, oxidizing agents have the ability to break these bonds and destroy molecules, including the ones that make up odour.

I have never had to confront Jerry’s particular problem, but I have had to deal with skunk odour. That was after I received a frantic call from a couple whose home had become unlivable after a skunk ventured into the basement and let loose. The stench just laughed at deodorizers and air fresheners, but finally surrendered to ozone. We just had to make sure no humans, animals or plants were around when the ozone generator was running, because ozone can attack molecules in living tissue.

In an ozone generator, invented by Nikola Tesla in the late 1800s, an electric spark passes through air and converts oxygen (O₂) into ozone (O₃). Tesla designed the generator as a device to battle air pollution, but that never materialized. The idea that ozone can purify air traces back to the particular smell, usually described as “fresh,” left behind after a lightning storm. That smell is ozone, produced when lightning, which is really just a giant spark, passes through air. The association of the “fresh” scent with “clean” and healthy is dubious, because while ozone can conceivably destroy some air pollutants, it is a toxic gas when inhaled. Indeed, there is concern these days that ground-level ozone, produced when sunlight triggers a reaction between hydrocarbons and nitrogen oxides in car exhaust, is a cause of respiratory problems.

The discovery of ozone dates back to the 1830s, when German-Swiss chemist Christian Schönbein became intrigued by the distinct scent he noted while carrying out electrolysis experiments in which an electric current passed through water to break it down into hydrogen and oxygen. He noted the smell seemed to be identical to that produced after a bolt of lightning. Schönbein managed to collect some of this gas and named it ozone from the Greek “ozein,” meaning “to smell.”

Not only did Schönbein manage to isolate ozone, he also developed an ingenious method of measuring the amount of the gas in a sample of air. His method was based on a previously discovered reaction in which starch reacts with elemental iodine to form a deep blue colour. Schönbein saturated a piece of filter paper with solutions of starch and potassium iodide, knowing that the iodide ion does not react with starch. However, in the presence of ozone, it is oxidized to iodine, which reacts with starch. The depth of the blue colour is indicative of the amount of ozone in the air. Today, ozone test strips make use of the same technology and can be used to detect levels of ozone in the air that would make it unsafe for children to play outdoors.

It is common for a newly discovered substance to be tested for different applications. As Louis Pasteur’s discovery of microbes’ link to disease slowly gained a foothold, substances, including ozone, were tested for their antibacterial activity. By the mid-1800s, ozone had been shown to eliminate microbes in water, leading to the construction of the first water treatment plant using ozone, in the Netherlands. Since then, the use of ozone in municipal water treatment has spread because, unlike chlorine, it does not leave any toxic trihalomethane residues. During the First World War, freshly generated ozone was directly aimed at wounds, in the hope of avoiding infection, but it did not work well and was soon replaced by sodium hypochlorite antiseptics, which did work.

While the value of ozone in water treatment and in disinfecting medical instruments has been well demonstrated, claims about the benefits of ozone to treat medical conditions are plagued by controversy. Since its introduction into medicine in the late 1800s, ozone has been touted as a treatment for everything from infections and diabetes to cancer and heart disease.

Today, the medical use of ozone is regarded to be in the “alternative” category because of conflicting evidence about its risks and benefits. Different modalities of administration are used. The gas is never inhaled — even Schönbein had reported that this can result in chest pain and breathing difficulties. Since ozone is unstable and cannot be stored for long before degrading to oxygen, it is generated just prior to use. It is then bubbled into water in which it readily dissolves, and this solution can either be injected or introduced intravenously. Another approach is to remove some blood from a patient, infuse it with ozone and return it into the circulation.

The most curious approach is to directly introduce ozone into the rectum or vagina via a catheter; proponents claim this can eliminate toxins, which are always unnamed. Gwyneth Paltrow apparently favours this method and has said she finds it “helpful,” without further elaboration. Then again, she has also said that inserting jade eggs into the vagina can increase sexual satisfaction.

All ozone treatments have one thing in common: They lack significant evidence of benefit. It would be incorrect to say there’s no evidence, because there is, perhaps surprisingly, extensive literature on the medical use of ozone, with some studies showing some benefit. However, the number of subjects is usually small, there is a lack of placebo control and followup times are short. Conditions that have no clearly effective treatment are the bread and butter of alternative therapists who capitalize on desperate patients willing to try anything. Fibromyalgia, arthritis, back pain and some cancers are in this category. Ozone therapy has been tried for all these, but reports of benefits are mostly anecdotal and not demonstrated by clinical trials.

In one of the better studies, injecting ozone into the knees of subjects suffering from osteoarthritis was compared with injection of corticosteroids. At 12 weeks, the ozone injections seemed to reduce pain somewhat more than the steroids, but the difference disappeared after six months. Not exactly an overwhelming result.

Still, the belief in the magical properties of ozone continues with ozonated olive oil, ozonated face creams, ozonated toothpaste and ozone saunas available for purchase. What isn’t available is evidence of efficacy. Except for eliminating skunk smell from basements.


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