Engineering Strategies for Airborne Diseases

E L E C T R I C A L S Y S T E M S T R A T E G I E S

AIR DISINFECTION – UVGI DISADVANTAGES

Human Exposure

• Occupational exposure guidelines for GUV in UV-C range have been developed by CDC/NIOSH. In room applications are usually limited to 0.2 W/cm2 for direct exposure. Exceeding the permissible exposure time can cause short- damage to eyes (irritation). No long- term damage has been documented.* • In-unit applications prevent human exposure and allow much higher irradiance.

Permissible exposure times for given effective irradiances at 254 nm wavelength

Material Degradation

• Paint can discolor under prolonged exposure. • Plastics can yellow under prolonged exposure.

* note: sunburn is caused by UV-B exposure. UV-C does not cause sunburn or skin cancer as it doesn’t penetrate the outer skin layer.