Germicidal Ultraviolet Lamps Disinfect Air But Also Transform Airborne Compounds Into Harmful Substances [STUDY]

Winter season also means flu season so people usually stay indoors to reduce their risk of getting infected. But this also presents a new opportunity for airborne pathogens to spread.

Germicidal ultraviolet lamps can help disinfect the air, but their UVC wavelengths also transform airborne compounds into harmful substances. American Chemical Society (ACS) researchers have modeled reactions by UVC sanitizing light and found a trade-off between removing airborne pathogens and producing air pollutants.

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An employee of the Chilean-Brazilian airline LATAM monitors the operation of an autonomous robot that uses type C ultraviolet light (UV-C) to clean the interior of the aircraft, amid the novel coronavirus COVID-19 pandemic, at Guarulhos International Airport, near Sao Paulo, Brazil, on November 20, 2020.

Disinfection or Air Quality?

Researchers reported in their study, titled "Model Evaluation of Secondary Chemistry Due to Disinfection of Indoor Air With Germicidal Ultraviolet Lamps" published in Environmental Science & Technology Letters, that they have modeled the reactions triggered by UVC sanitizing light and found a trade-off between disinfection and reducing the air quality.

Disinfecting UVC lamp systems have been a cost-effective way to rapidly inactivate airborne pathogens indoors and one design shine at 254 nm, which could damage human skin and eyes, which is why it should be mounted near the ceiling or inside ventilation ducts. Meanwhile, a UVC lamp that shines light at 222 nm can be used for whole-room disinfection and is safer for humans.

But UVC light can still set off many reactions that could break apart molecules in the air and form strong oxidants, like hydroxyl radicals and ozone, Phys.org reported. These oxidants can convert volatile organic compounds in the air into peroxides and carbonyl compounds that can be further broken up and turned into organic radicals.

These organic radicals can generate additional VOCs and reduces air quality which could human health. However, the levels of compounds generated from these secondary reactions from UVC lamp systems are not yet studied. So, researchers used computer models to evaluate the possible impact of two UVC air cleaning systems on disinfection and air quality.

Researchers estimated that the virus removal rate and amount of secondary VOCs generated in three indoor scenarios indicated that both UVC wavelengths significantly decrease the risk of infection compared to ventilation alone. More so, the models projected that the systems would initiate secondary reactions with VOCs in indoor air.

Based on the results, the team recommends the use of GUV systems in environments at high risk of airborne pathogen transmission where the benefit of removing airborne pathogens outweighs the impact of air pollutants.

Germicidal Ultraviolet Lamps at Work

Germicidal ultraviolet lamps produce UVC light that deactivates the DNA of bacteria, viruses, and other pathogens to destroy their ability to multiply and cause disease, as per Ultraviolet.com. UVC light specifically targets the nucleic acid of microorganisms by forming covalent bonds in certain adjacent bases in the DNA, preventing replication.

Unlike most disinfection methods, germicidal ultraviolet technology does not use chemicals, is simple, inexpensive, and requires very low maintenance. They are used in drinking water, medicine, food processing, cosmetics and electronic production, laundry water, pond and lake reclamation, and many others.

UVC lamps are electronic products that are regulated by the Food and Drug Administration, whether it is for medical or non-medical use, through the Electronic Product Radiation Control Provisions enacted under the Radiation Control for Health and Safety Act.