UV Air Purifier Guide
Ultraviolet light (UV) is a form of radiation with very short wavelengths – too short to be perceived by the human eye. Some air purifiers include specialized lights that produce ultraviolet rays as a way to kill microbial contaminants. Unlike filters, which collect pollutants as they pass through the purifier, the purpose of ultraviolet light is to kill bacteria, mold, and viruses. UV light can penetrate the outer structure of a microorganism’s cell and alter its DNA, permanently preventing replication and causing cell death.
According to the Environmental Protection Agency (EPA) there is no standard measurement of the effectiveness of UV air purifiers. Effective destruction of some viruses and most mold and bacterial spores usually require much higher UV exposure than is provided in a typical home unit. Still, an UV light air purifier will kill most of the bacteria, viruses, molds and yeasts that pass through its light chamber. Unfortunately they will not capture dust, allergens, or solids in the air. Thus, UV air purifiers do not appear to be as effective as a sole control device. When UV air cleaners are used they should be used in addition to, not as a replacement for a conventional air filtration system. UV light targets only one kind of air pollution. They do not prevent other common types of air pollution such as Volatile Organic Compounds or particles such as dust.
Two types of UV air purifiers
There are two types of UV air purifiers: airstream disinfection and surface disinfection. Airstream disinfection is designed to reduce the viability of vegetative bacteria and molds but require a very high dosage in UV to be very effective. In order for an airstream disinfection application to work there must be a fan to create air movement or else disinfection will not take place. UV purifiers with surface disinfection are installed in air-handling units to prevent or limit the growth of vegetative bacteria and molds on moist surfaces inside the purification system.
UVGI – Ultraviolet Germicidal Irradiation Cleaners use ultraviolet radiation to destroy biological pollutants such as bacteria, viruses, and molds using airstream disinfection or surface disinfection.
POC – Photocatalytic Oxidation Cleaners use a UV lamp along with a substance called a catalyst that reacts with the light. They are designed to destroy gaseous pollutants by converting them into harmless products, but not remove them entirely.
Ozone Generators – Use UV light to intentionally produce ozone to kill contaminants. Ozone is a lung irritant that can cause adverse health effects. Thus, ozone generators are not always safe and effective at controlling indoor air pollutants because of the by products they produce.
- Well designed Ultraviolet air purifiers can reduce vegetative bacteria, molds, and some viruses.
- Mold is still dangerous to humans even if it is dead; the only solution to mold is to have it removed.
- Ineffective against particles like dust, dust mites, and allergens. May not reduce allergy or asthma symptoms.
- Further research has still not been able to measure absolute effectiveness.
- Most air purifiers that use UV lights do so as a secondary feature, complimenting other methods or air purification such as HEPA filters.
- The best way to address this risk is to control or eliminate the sources of pollutants, and to ventilate a home with clean outdoor air. If these measures are not enough, an air cleaning device will always be useful.
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