Ozone is gas consisting of a single element – oxygen. Ozone can be depicted as a ordinary O2 molecule with a highly nervous, active, reactive, irritate, energetic and virile O1 atom. It is active and reactive.

Ozone is a powerful antimicrobial agent and is usable in food industries when in gaseous or liquid state. Molecular ozone or its decomposition products have the ability to rapidly deactivate microorganisms by reacting with intercellular ferments, nuclear matter and components of its cell membrane, spore vessels or virus capsids. Ozone used in food industry is generated on site and it rapidly disintegrates without leaving any residue. Ozone is suitable to decontaminate products, equipment, surfaces coming into contact with food and processing environment.

The basis of the industrial production of ozone is plentiful and inexhaustible resources of O2. Ozone (O3) is formed as a result of atom rearrangement in oxygen molecules under the impact of a high voltage electric discharge. The product is a pale blue sharp odour gas with a high oxidizing potential. Ozone is formed in the process of reaction of free oxygen radicals with oxygen molecules by forming triatomic oxygen molecules, or trioxygens. In addition to photochemical and electric discharge methods, ozone can be produced using chemical, thermal, chemonuclear and electrolytic methods. For commercial purposes ozone is usually produced by using corona discharge method.

Two electrodes, one high voltage and the other low voltage, separated with a special dielectric provide a narrow gap for discharge. Electrons, having kinetic energy sufficient to decompose oxygen molecule, collide with them and an ozone molecule may be formed from each oxygen atom. When ambient air is flown through an ozone plant, 1-3% of ozone is produced; whereas using high purity oxygen, up to 16% of ozone can be produced. Thus, ozone concentration may not be increased beyond the point when the formation and disintegration rate is equal. Ozone is produced on site where it is used because it may not be stored due to its spontaneous decay into oxygen atoms.

What is Ozone (O)

We know from the course in physics that the ozone layer, located at the height of 14 to 20 km above the Earth, protects our planet from harmful Sun’s rays. When this layer depletes the life is exposed to increasing threat, which enhances when the so-called ozone holes are formed in the layer.
At thunderstorms some ozone gets into atmosphere, goes down and the air is suddenly filled with the “smell of the sky”. Ozone is derived from the Greek word meaning “to smell”. One can feel freshness and cleanliness after a thunderstorm. Such minute amount of ozone cleans the air and makes breathing easier. This pleasant sensation lasts shorter in a city where the air is polluted. The smell of smog kills the odour of ozone. Only in the country one can feel ozone better and it is reminiscent of a mild flavour of withered roses. Everyone without exception likes this odour. It is said that the heart comes to life because of this odour. Why? The reason lies in the fact that, when decaying, ozone O3 releases oxygen which is necessary to any living creature. Especially city people feel lack of ozone. We complain about health because our cells feel hunger, they are short of oxygen.
Ozone is widely used as a disinfectant in water treatment, food production and storage, and for various other purposes. As oxidant, ozone may be effectively used in the food industry due to its advantages over conventional methods of food preservation. Ozone in its gaseous or liquid state is often used for inactivation of pathogens and obnoxious microorganisms in fruit and vegetable processing. In addition to inactivating a wide range of microbes, ozone may be applied to kill warehouse pests and reduce mycotoxyns. One of the advantages of ozone is spontaneous decay of excessive ozone back into oxygen without leaving any residues in food. It has been determined that ozone is an efficient agent against various microorganisms, including bacteria, fungi, viruses, protozoa and spores of fungi and bacteria. These advantages make ozone attractive in the food industry therefore it has been Generally Recognized as Safe (GRAS) for applications in food processing.

Ozone Effects on Viruses and Bacteria

Ozone breaks through the cell membranes of microorganisms (bacteria, viruses, fungi, moulds), while paralysing respiratory system of insects and rodents. Since plant cells are bigger than those of microorganisms, have a multilayered structure of cell walls and are adapted to a short-time working of ozone at low concentrations, they are not exposed to the effects of processing.
The use of ozone does not leave any residue of toxic substances.

Ozone’s Effects on Human Health

There is a vast shortage of information on ozone in Lithuania. This might be the reason why ozone use is not widespread. Lack of knowledge misrepresents information, sometimes, such knowledge is even falsified. It is unreasonable and senseless to speak of hazards or toxicity of ozone. Now, when there is such shortage of safe methods of prevention and therapy, ozone could solve a lot of old and burning issues in many areas. Ozone is safer and it has no toxic effects. Very small doses of ozone can improve life quality of many seriously ill patients, especially those suffering from such grave illnesses as diabetes, psoriasis, and other problems of skin, digestive tract, heart and cardiovascular diseases.
Ozone does not claim to be panacea, it is, however, regrettably when people and companies, which could otherwise use ozone for treatment of water and air, decontamination of raw materials and equipment, do not possess full information or are misled by myths on supposedly harmful effects of ozone. These theoretical fears are based on the third atom of ozone O3 – active oxygen. Its amount is strictly dosed. Oxidation is a process when viruses, bacteria, pests and not cells are killed, because they do not have membrane protection from the effects of ozone. This is exactly what makes the use of ozone unique.

Human cells have immune system and are not afraid of oxidation. Micro doses of ozone do not pose any threat to human cells, because ozone primarily oxidises the cells which are dead, damaged, virus contaminated, and destroys pathogenic organisms as such. That means that ozone at minimum doses is not only safe but it also has a healing effect. We are made up of 75 % water, and what do we drink? The well water is highly polluted with nitrates, nitrites, and harmful organisms. This is the fact that concerns hygienists. It appears that the God of Thunder does not come to the rescue of a person living in the country anymore; they also need the help of ozone.

Today aquatic entertainment has become widespread; families with little children spend their time in water pools. And what kind of water is there? What do children breathe (through the skin and lungs) for long hours? Therefore, it would be very desirable that the companies engaged in rural tourism apply ozonation for water pool and bath water. It would make a perfect additional benefit for human health. The World Health Organization has been frightening with the danger of pandemic influenza for several years. And what will happen if such influenza does appear? What will protect us? What? Ozone only. Not people alone will need ozone but livestock and poultry will need it also. With this “smelling cloud” on the farm, we will protect livestock and poultry from the threat of pandemic and bird flu (avian influenza). People in cities live together with their four-legged friends and catch parasites from them. And what prevents cafés or restaurants from offering a glass of fresh ozonated water to visitors already today? It is an original and delicious service. A wonderful property of ozone is its ability to supply organism with oxygen. Not everyone is aware of the fact that it is exactly ozone that pathogenic organisms, giving rise to cancer, diabetes, heart and cardiovascular problems, thrombophlebitis, psoriasis and many other so-called “incurable” or “fatal” diseases, are afraid of and from which they perish .

Ozone Concentration Measurement Methods

Physical, physical-chemical and chemical methods have been used to measure ozone. Physical methods are used to measure direct ultraviolet radiation (UV) absorption in the visible or infrared spectrum part. Physical-chemical methods are dependant on such factors as the heat released by reaction or chemical luminescence. Chemical methods are used to measure the amount of products produced as a result of the reaction of ozone with chemical reactants such as potassium iodide.


Product / substance

Molecular formula

Main characteristics

Oxidising gas – CAS No. 10028-15-6 / EG No. 233-069-2

Molecular weight

electric discharge method

Up to 18 % by weight in oxygen/oxygen-enriched air

Boiling point
-111,0 ° C,

Melting point
-192,7 ° C,

Solubility in water
by weight (at 20 ° C) 0,003 g / l (3 ppm)

Vapour density
1.6 (1 = air)


non-flammable/vigorously supports combustion

Appearance and odour
Ozone is colourless at all concentrations. It has a pungent characteristic odour usually associated with electrical sparks. The odour is generally detectable by the human nose at concentrations of 0.05 ppm.

Fire/Explosion and hazard data
Ozone is a powerful oxidising agent. Oxidation with ozone evolves more heat and usually ignites at a lower temperature than oxidising with oxygen. Ozone reacts with non-saturated organic compounds to produce ozonides, which are unstable and may decompose with explosive violence. Ozone is an unstable gas that, at normal temperatures, decomposes to molecular (biatomic/diatomic) oxygen. At elevated temperatures and in presence of certain catalysts such as hydrogen, iron, copper and chromium, this decomposition may be explosive.

Flash point
Not applicable

Auto ignition temperature
Not applicable

Reaction data and conditions contributing to instability of ozone
Ozone spontaneously decomposes under all ordinary conditions, so that is not normally encountered except in the immediate vicinity of its production. Decomposition is accelerated by contact with solid surfaces, by contact with chemical substances and by the effect of heat.

Ozone is a powerful oxidising agent and reacts with all oxidising materials, both organic and inorganic. Some reaction products are highly explosive.

Hazardous decomposition products

Permissible Exposure Limits

The following limits are widely accepted (USA, Sweden, UK and other parts of Europe):

– 8 hours per day/5 days per week (occupational exposure limit) – 0.1 ppm

– 15 minutes (short term exposure limit) – 0.3 ppm

Toxicity of ozone
The acute and chronic effects of excessive exposure to ozone have been well investigated. Exposure to concentrations of ozone in excess of several tenths of a ppm sometime cause reports of discomfort in a small susceptible portion of the population. This can be in the form of headaches of dryness of the throat and mucous membranes of the eyes and nose following exposures of short duration. Repeated exposure to ozone at such concentrations at 24-hour intervals, however, caused no further increase in irritability of respiratory system, throat or mucous membranes, eyes or nose. In fact after the first exposures, additional exposures to ozone had progressively lesser effects suggesting that tolerance may develop over time.

Ozone has been shown to be more injurious at concentrations exceeding 2.0 ppm over several hours, such as experienced by gas shielded arc welders. The primary site of acute effects is the lung. This acute impact subsided in welders when exposures where reduced to less than 0.2 ppm. Based on animal studies, exposure over 10 to 20 ppm or an hour or less believed to be lethal in humans although there has never been a single recorded fatality attributed to ozone exposure in more than 100 years of commercial use. (Compare with this experience with Chlorine as which has claimed many victims in peacetime as well as during war).

With respect to long term or chronic toxicity, ozone is a radiomimetic agent, i.e. the effects of long term exposure to excessive ozone exhibits the same affects as excessive exposure to sunlight. These effects are drying of the dermal surfaces and general ageing of exposed tissues. Ozone is not generally regarded or suspected of being a human carcinogen, neither does in exhibit tertogenic or mutagenic properties.

In the event of an ozone leak:
1. Ventilate the area
2. Immediately switch the ozone generator off
3. Stop the flow of ozonated water
4. Where high levels of ozone are experienced (in excess of 0.1 ppm) all personnel should vacate the affected area until it has been thoroughly ventilated.
5. When ozone levels in excess of 0.3 ppm are present, or when personnel are required to work in restricted spaces or tanks, where ozone my be present, only persons wearing suitable breathing apparatus should be allowed in the area.

• Eye exposure – If ozone gets into the eyes, wash immediately with large amount of water, lifting the upper and lower eye lids occasionally. Seek medical attention as soon as possible

• Breathing – If a person breaths in large amounts of ozone, move the person into warm un-contaminated air at once. If breathing has stopped, perform artificial respiration. When breathing is difficult, properly trained personnel may assist by administering breathing oxygen. Seek medical attention as soon as possible.