Is There an Optimal Wavelength for Germicidal Ultraviolet Air Disinfection?

Area of Science:

• Environmental Health
• Photochemistry
• Infectious Disease Control

Background:

• Germicidal UV (GUV) disinfection effectively targets airborne pathogens but may increase indoor air pollution.
• Conventional GUV (254 nm) is limited to upper-room use, while Far UVC (222 nm) allows whole-room application due to safety.
• Development of new GUV wavelengths necessitates guidance on their comparative benefits.

Purpose of the Study:

• To investigate GUV wavelengths between 185 and 310 nm.
• To identify an optimal GUV wavelength balancing disinfection efficacy and safety.
• To assess GUV-induced indoor air pollution risks across different wavelengths.

Main Methods:

• Modeling GUV disinfection between 185-310 nm.
• Evaluating health risks from GUV-induced air pollution (ozone and particulate matter).
• Comparing pollution risks at constant disinfection rates (5 and 20 eACH).

Main Results:

• GUV-induced air pollution risks are at least 20 times higher below 242 nm compared to above 242 nm.
• Ozone production from O2 photolysis and VOC oxidation contribute to pollution below 242 nm.
• Upper-room GUV shows an advantage over Far UVC regarding indoor air pollution.

Conclusions:

• No single GUV wavelength optimizes all criteria (safety, disinfection, pollution, logistics).
• Wavelengths above 242 nm present a lower indoor air pollution risk.
• Far UVC use may require concurrent air cleaning for pollution mitigation.