Manufacturers promise quick help
An ozone treatment of indoor air promises quick relief from all kinds of unpleasant odors in the home. For example, it can smell significantly bad after a smoldering fire, mold growth, or in the case of a smoker’s apartment. Numerous providers promising a solution using ozone generators can be found in search engines. The following article examines the advantages and disadvantages of ozone treatment, sheds light on the chemical processes involved, and evaluates opinions from users of these devices. The topic seems to be of interest. The website of https://www.baubiologie-regional.de can point to hundreds of search terms related to the term “ozone treatment.”
What chemical processes take place during air purification with ozone?
During oxidation with ozone, chemical reactions occur in which ozone (O₃) acts as an oxidizing agent, taking electrons from other substances. In industrial processes, this leads to the formation of new products, or in air purification, to the breakdown of substances. Ozone is a particularly strong oxidizing agent and can effectively break down organic compounds, odor molecules, and some inorganic substances. These compounds can be of natural origin or come from human activities, such as solvents, benzene, formaldehyde, and other volatile organic compounds (VOCs). The oxidation of these compounds by ozone often leads to their decomposition into smaller molecules that are less harmful or odorous. Ozone can also effectively kill microorganisms such as bacteria, viruses, and fungi. This occurs through direct oxidation of the cell walls or outer membranes, leading to cell death.
Use of ozone devices in residential areas
An ozone generator draws in ambient air and directs it into the device. Through the use of electrical discharges (corona discharge) or UV light, oxygen (O₂) in the air is converted into ozone. In the corona discharge method, the oxygen molecules are broken apart by an electrical discharge, releasing individual oxygen atoms, which then combine with other oxygen molecules to form ozone. The UV light method uses a specific wavelength of UV light that splits oxygen molecules into individual atoms, which then also combine to form ozone. The produced ozone then enters the room or environment to be treated and oxidizes the existing substances. After oxidation, the ozone eventually decomposes back into oxygen. That’s the theory – practical problems that may arise are discussed below.
Guidelines or standards for the application of ozone treatment in indoor air
In Germany, there are specific limits for the concentration of ozone in the air, set by the Federal Environment Agency. The maximum 8-hour value for ozone is 120 micrograms per cubic meter (µg/m³), which may be exceeded on no more than 25 days per year, with the recommendation that exceedances should ideally be avoided altogether. There is an information threshold at a 1-hour average value of 180 µg/m³ and an alarm threshold at 240 µg/m³. When using ozone generators indoors, these limits must be observed to ensure that the ozone concentration does not reach harmful levels. In the field of occupational safety, irritation of mucous membranes, odor nuisance, and changes in lung function have been observed only at concentrations greater than 400 µg/m³. For safety, the ozone concentration in indoor air should be measured. Devices available on the market use electrochemical sensors to measure ozone molecules in the air, where a change in the electrical current in the sensor indicates the ozone concentration.
What harmful effects of ozone on health are known?
Ozone is absorbed exclusively through the mucous membranes of the respiratory tract (mouth, nose, and throat) as well as the eyes. Absorption through the skin is seemingly negligible under practical conditions. Acute main effects at higher concentrations in work processes include irritation or damage to the mucous membranes of the eyes and respiratory tract, changes in lung function, and impairment of physical performance. At high concentrations, lung damage and general malaise in the form of headaches, nausea, or concentration problems can be triggered.
How long does the process of ozonation take, and when can the room be used again afterward?
The duration of an ozone treatment and the time one should wait before re-entering the room depend on various factors, including the duration and intensity of the ozone treatment, room size, ventilation, or the original contamination. Manufacturer instructions must be followed carefully. In private homes, ozone treatments typically last from 30 minutes to one hour. After an average ozone treatment, it is recommended to wait at least 1 to 2 hours before re-entering the room. The room should then be thoroughly ventilated to remove any remaining ozone. The emitted ozone should not be inhaled under any circumstances, and houseplants and food should be removed from the rooms.
What practical problems can arise during the application of ozone treatment?
The ozone device should operate on a timer to ensure that users do not inhale ozone. If necessary, an external timer can be used. The dosage should be adjustable to accommodate room size. Problems arise when the ozone smell remains in the room for several days despite continuous ventilation. It can either smell like “sunlamp” or chlorine. There are also repeated reports that bad odors return after ozonation, for example in smoker’s apartments or cars. In another case, it was reported that the ozone smell became embedded in the mattress and bedding.
What alternatives are there to ozone treatment?
The causes of odor problems should definitely be investigated. If the room smells musty, bacteria or fungi may be the cause. In that case, there is a moisture problem in the room. Mold and bacteria should not be preemptively fought without clear warning signs. In smoker’s apartments, wallpaper must be removed, and sometimes plaster must be renewed. In the case of tar-like smells, old adhesives are often the cause. In these cases, the flooring and adhesive should be removed. In prefabricated houses from the 1970s, chloroanisoles are responsible for the bad smell. Ozonation would only be effective in the short term because the chemicals in the building materials continuously produce new odors. If renovation is not possible, controlled ventilation might be an option.
Original article in German