Introduction: Ultraviolet Light
Ultraviolet (UV) light is a form of radiation with very short wavelengths—too short to be perceived by the human eye. This form of energy is called “ultraviolet” because it has shorter wavelengths than violet light, which has the shortest waves of any kind of visible light.
Although UV radiation can be dangerous, and you can often hear reports about the dangers of UV rays coming from the sun, ultraviolet light is not always detrimental to humans and has a variety of uses. Some air purifiers include specialized lights that produce ultraviolet rays as a way to kill living pollutants.
EPA Studies – Effectiveness of UV Air Purifiers
Based on the available test information, the actual success rate of UV purifiers is mixed. According to the EPA’s official guide on indoor air cleaners, well-designed ultraviolet air cleaners are able to:
“[Air purifiers] reduce the viability of vegetative bacteria and molds and to provide low to moderate reductions in viruses but little, if any, reduction in bacterial and mold spores.”
Factors Influencing UV Air Purifier Effectiveness
It also states that various factors influence the effectiveness of UV purifiers, including
- UV irradiation dose
- System design and application
- System operation characteristics
- Microorganism targeted for deactivation.
Thus not all UV air purifiers are the same, and UV lights will be more or less useful depending on the environment they are placed in.
Furthermore, tests have shown that UV cleaning alone does not reduce dust mite problems or allergic reactions to mold—the latter because mold is still dangerous to humans even if it is dead. The Environmental Protection Agency states that the only solution to mold is to have it removed. Ultimately, the EPA declares that further testing is necessary in order to better understand just how useful ultraviolet air cleaners really are.
Conclusion – Ultraviolet Air Purification Effectiveness
- Well designed systems can reduce vegetative bacteria, molds, and some viruses
- Little if any reduction in bacteria or mold spores
- Ineffective against particles like dust or dust mites
- Further research is needed to measure absolute effectiveness
Sources referred to in this article:
- United States Environmental Protection Agency. “Residential Air Cleaners (Second Edition): A Summary of Available Information — Ultraviolet Germicidal Irradiation Cleaners.” http://www.epa.gov/iedweb00/pubs/residair.html#Ultraviolet_Germicidal_Irradiation_Cleaners
- Wikipedia. “Ultraviolet.” http://en.wikipedia.org/wiki/Ultraviolet