An air purifier is a device designed to reduce domestic and industrial pollution. It filters the air, removes certain pollutants, as well as bad odors. Air purifiers are used by industry to filter and remove toxic residues, in hospitals and airlines to prevent the spread of viruses and bacteria. They are also used in offices and homes to improve hygiene, the quality of life of each individual and reduce the risk of contagion and disease. Domestic pollution is linked to the presence in the air of three types of pollutants:
- Particulate matter: these are suspended particles (fine particles, pollen, hair, mites, etc.) ;
- Chemicals, such as volatile organic compounds (VOCs), or nitrogen oxides ;
- Biological: viruses, bacteria, molds.
These pollutants are carcinogenic and allergenic. Domestic pollution is caused by car exhaust, household product residues and the building materials used. It greatly increases the mortality rate of assets. Many household products (detergents, home fragrances, etc.), and some building and renovation materials (solvents, carpets, paints, etc.) deteriorate air quality and are a major cause of serious illness. 70 to 90% of our time is spent in enclosed spaces and humans breathe more than 15,000 litres of air a day, making indoor pollution a significant health threat.
The air purifier aims to reduce overexposure to pollens, allergens, and microbial (viruses and bacteria) and chemical (detergents, solvents and nitrogen oxide) air pollutants. Many companies offer solutions to treat the air in your home individually, but there is no standard for air treatment. For domestic and industrial pollution treatments, there are generally six types of air purifiers.
Filter purifiers do not destroy household pollution. They filter it either from high-capacity filters; or by means of an ionizer. To destroy air pollution and volatile residues, another type of purifier should be used in addition.
The HEPA filter (High Efficiency Particulate Air filter) is used to filter allergens and pollens, but remains useless for chemical pollutants. Depending on its classification, it can filter more or less fine elements, even filtering bacteria and viruses in some cases. The least thin filters are used in many applications: air conditioners (for domestic use, offices, cars, planes, etc.), vacuum cleaners. Their cost is low, which allows them to be used extensively in air handling systems. The finest filters are used in hospital settings and clean rooms. Their cost is high, and the procedure for replacing the filter is strict, which reduces its possibilities for domestic and individual use. The HEPA filter has no action on chemical pollutants (household detergent, air pollution, etc.). In domestic use, it is not thin enough to have any action on viruses.
Air purification by ionization produces an electrical reaction: it generates negative ions (anions) that amalgamate the fine particles in suspension. By negatively charging them, dust, allergens, pollens, mold spores and biocontaminants are attracted to the soil and removed from the ambient air. Air ionization is a silent, energy-efficient and environmentally friendly technology. It is effective against nanoparticles.
Combustion air purifiers destroy particles by burning harmful particles or raising the air temperature. They release purified air but increase the concentration of ozone (O3) in the air, generate an unpleasant odor and increase the ambient temperature.
Cold plasma air purification is a technology that propels the air purifying device in its plasma form. In this form, free radicals in the air readily oxidize and destroy harmful particles (VOCs) and viruses. The photocatalysis air purifier combines the filtration of volatile particles and the destruction of viruses and bacteria, solvents, detergents and nitrogen oxides (NOx). In contact with ultraviolet light, the catalyst (titanium dioxide) becomes an oxidizer that destroys odors, volatile organic compounds (VOCs), allergens and pollens), residues of chemical and atmospheric pollution such as nitrogen oxides released by exhaust pipes. The catalyst also destroys bacteria and viruses. It consists of a fan, which captures particles, a UV-A (or UV-C) ultraviolet lamp, and a catalytic media, for example titanium dioxide (TiO2).