How UV Lighting Can be Used as a Disinfectant for Your Facility

UV lighting can be used as another tool in your safety and environmental arsenal to make your workplace safer and healthier.  But how does it work?

What is UVGI?

Ultraviolet Germicidal Irradiation, or UVGI, is a technology that goes back to the 1930’s with studies showing that ultraviolet light has the ability to kill or inactivate airborne microorganisms. These studies showed that an optimal wavelength of 265 nanometers (nm) was able to provide the largest reduction in airborne microorganisms. This was found to be very close to the wavelength produced by low-pressure mercury vapor lamps (254 nm).

Ultraviolet light can be broken down into 4 different bands:

• UV-V: 10-200 nm
• UV-C: 200-280 nm
• UV-B: 280-315 nm
• UV-A: 315-400 nm

The sun emits the full spectrum of ultraviolet light but only UV-A & UV-B make it to the surface.  The others are filtered out by the Earth’s atmosphere.  The UV-C band is the most effective at attacking the harmful microorganisms, so it needs to be generated artificially.

How does UVGI work?

UV-C wavelengths are readily absorbed by the DNA and RNA of microorganisms such as germs and mold.  When absorbed, UV damages their DNA or RNA structure, preventing the microorganism from replicating. The magnitude of their reduction is affected by their resistance to UVGI, the quantity of UV energy delivered, and the type specific microorganism being irradiated.

Disinfecting light is delivered in two common methods. The first is by placing light units, either with or without fans, near the top of a room close to the air vents in order to clean the air as it circulates the room.

The second method is to place the unit directly into the heating and air conditioning (HVAC) system. This second method places the light in a location where the room occupants are not directly exposed to the light, and if placed correctly, can have an added advantage of cleaning the HVAC coils and drip pan to improve the efficiency of the HVAC system.

The design and placement of these different systems are governed by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) which has published many documents on the subject.

UV Safety Considerations

UV-C band light is a safer band than the UV-A and UV-B that we deal with in nature. We have always been taught to apply sunscreen and wear sunglasses to protect ourselves from the burns we receive when outside. Due to the shorter wavelengths UV-C will only penetrate the outer skin layers and along the surface of the eye. It will not give you the severe sun burn the longer wavelengths will. It will cause a reddening and slight irritation of the skin and an painful itching sensation that will last a few days in the eye so slight protection is required if you are directly exposed to the light from these units.

UV Lighting for Your HVAC Units

iSi is now providing the second method UV germicidal lighting, the one for your HVAC system.  Our units are customized to your specific HVAC system and area to be disinfected.  Learn more about this service and get a quote here.