Improving indoor air quality with germicidal ultraviolet (UV) light has been used since the 1950s in food preparation and in medical applications. Due to a lack of fresh air and ventilation, residential and commercial air quality has become an issue, causing serious health problems. Heat, ventilation, and air conditioning equipment, along with enclosed spaces, can harbor fungi (mold and spores) airborne viruses, and bacteria. With the development of products described below, there are now various configurations of fixtures using germicidal UV light that can be used to protect against infection due to airborne microbes.
UV germicidal lamps used for disinfection are short wave, low-pressure tubes producing ultraviolet wavelengths that are lethal to microorganisms. UVGI air or surface disinfection systems are designed to improve indoor air quality. Germicidal lamps should not be confused with sunlamps or blacklight lamps. While these are also ultraviolet lamps, the UV produced is of a longer wavelength and is not useful for germicidal applications. Susceptibility to UV light varies between these microbes, requiring varying doses (measured in millijoules/cm2).
Method 1: Ultraviolet Air Duct Disinfection for Improved Indoor Air Quality
(For use in residential, commercial and industrial applications)
UV air duct disinfection is a practical solution for indoor air quality in hospitals, schools, commercial buildings, and homes. With the proper system design and installation, germicidal ultraviolet light is highly effective at treating moving air. Typical residential systems are sized for a minimum nominal 80% bacteria inactivation rate, commercial applications for 90%, and up to a 98% inactivation rate essential for hospitals and pharmaceutical laboratories.
Installation of air duct disinfection fixtures is recommended to be perpendicular to the airflow. This method is most effective, as the lamp rays will travel the full length of the duct — increasing the exposure time. Lamps mounted parallel to the airflow will only radiate out towards the wall of the duct and treat air as it passes by. Mounting the fixture requires cutting a hole within the duct wall to insert the lamps crosswise and supporting it to the wall of the duct with brackets.
Once installed, it is normally recommended that the unit remain on continuously and not be cycled off and on with the fan of the air handler. Cycling of these germicidal lamps may reduce their rated life.
Germicidal UV fixtures are sized based on time and intensity — that is, time that the air and surfaces are in contact with germicidal UV light, and the intensity of the fixtures to be used. Note that multiple fixtures may be needed in some cases to increase the intensity and meet indoor air quality requirements. The following information is needed to size an UV system for duct air treatment:
- Duct or plenum size
- Length of compartment or duct where units are to be installed
- Air speed typically provided in CFM (cubic feet per minute)
- Approximate air temperature
To calculate the approximate contact time and lamp output needed for each application, this information should be presented to an UV application specialist at the manufacturer’s facility. Then, a recommendation of fixture size and quantity can be made.
Systems can be provided with lamp operation indicators to confirm germicidal UV lamp operation. Currently, there are systems available with a UV-blocking glass window, which mounts to the duct wall, or an LED display either on the housing of the fixture or remotely installed.
Method 2: UV Room Air Sanitizers for Improved Indoor Air Quality
(For use in residential, commercial, and industrial applications)
Another germicidal UV alternative for improving indoor air quality (especially if duct installation is not available or practical) is the use of room air sanitizers. These products are self-contained UV exposure chambers. Fixtures are available in many configurations to adapt to any setting.
UV room air sanitizers can be mounted in a ceiling, on a wall, or are available for portable use. Air is drawn into the fixture through an electrostatic particulate filter and forced into ultraviolet exposure chamber where it is irradiated by UV light. Purified air leaves the exposure chamber through a louvered exhaust panel. Fixtures can be sized based on the room size and air changes per hour required by the application.
There are several advantages to using systems with this type of design. For starters, fixtures can be tailored to supply the room air changes needed (blowers control the air flow through the chamber). In addition, installation is easy and inexpensive. Just mount the unit (if needed) and plug it into an outlet. Since a properly-designed fixture will hold UV rays within the exposure chamber, it won’t pose any risk of accidentally exposing room occupants.
Various features and options are available on these types of UV fixtures to make them ideal for specific applications. Portable models also add more versatility.
There are several advantages to using systems with this type of design. For starters, fixtures can be tailored to supply the room air changes needed (blowers control the air flow through the chamber). In addition, installation is easy and inexpensive. Just mount the unit (if needed) and plug it into an outlet. Since a properly-designed fixture will hold UV rays within the exposure chamber, it won’t pose any risk of accidentally exposing room occupants.
Various features and options are available on these types of UV fixtures to make them ideal for specific applications. Portable models also add more versatility.
Method 3: UV Upper Air Disinfection Equipment for Improved Indoor Air Quality
(for use in commercial and industrial applications)
If air duct models or room air sanitizers are not ideal, there is another choice for improving indoor air quality: upper air disinfection. Upper room systems run continuously in occupied areas, reducing the risk of cross infection from airborne microbes.
As germicidal UV rays are projected across the upper room air, these fixtures destroy bacteria and viruses carried into the UV field by convection currents or air circulation. When applying indirect germicidal UV to upper air, radiation in the room below 6-1/2 feet must be kept within acceptable limits (3.0 millijoules per square centimeter for eight-hour exposure, as specified under the ICNIRP guidelines for UV safety). Therefore, mounting in the proper position is essential for safe use. Occasional UV measurements will be needed to ensure that ultraviolet intensities are within the allowable exposure limits. Some fixtures use variable output ballasts that can be adjusted to follow the standard.
This type of fixture is relatively efficient due to the long, unobstructed path of the UV rays. Occupied areas can be treated without the need for special precautions or protective clothing.
UV Equipment Maintenance for Improved Indoor Air Quality
UV equipment maintenance consists of cleaning the lamps periodically to ensure maximum output. Lamps should be replaced once a year. In addition, easy-to-use handheld meters are available to check the intensity of aging UV lamps and ensure the exposure of room occupants is within acceptable limits.
UV equipment maintenance consists of cleaning the lamps periodically to ensure maximum output. Lamps should be replaced once a year. In addition, easy-to-use handheld meters are available to check the intensity of aging UV lamps and ensure the exposure of room occupants is within acceptable limits.
3 Product Lines for Improving Indoor Air Quality
Atlantic Ultraviolet Corporation has a product line for each disinfection method described above. AeroLogic® 
UV-C Air Duct Disinfection fixtures are available in varying sizes and intensities for residential, commercial, and industrial settings. Sanitaire® UV-C Room Air Sanitizer models are available in 3 varieties: wall mounted, for drop-ceilings, or mobile. Hygeaire® UV-C Indirect Air Disinfection models (wall mount or pendent mount) are the result of extensive research. The angle of their polished reflector projects UV rays at just the right angle to ensure the safety of room occupants.
Hygeaire®…AeroLogic®…Sanitaire®…which is the best model for your application? Call a UV Application Specialist today!
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- Call (631) 273-0500, Monday – Friday 7am to 6pm EST
- Email Sales@AtlanticUV.com
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