UVC Indirect Upper Air Sanitizers
Ultraviolet UVC indirect upper air and surface fixtures use germicidal light bulbs and louvers to direct the UV light rays to the upper portion of air in rooms. They are installed at least seven feet above the ground, and are designed to be used in occupied spaces. They can be mounted on walls or ceilings in a corner, along a linear portion of the wall, or hanging from the ceiling with a pendant mount. Common applications include hospitals, laboratories, operating rooms, burn centers, doctors offices, homeless shelters, methadone clinics, and dairy plants.
About Upper Room UVC Fixtures
Ultraviolet upper air systems direct germicidal irradiation to the upper portion of a room, including the air and ceiling surface. As warm air rises in a room and enters the irradiation zone of the fixture, it is disinfected. Then, as the purified air cools, it falls.
These fixtures are designed to be mounted at least seven feet above the ground. This ensures humans and animals in the room are protected from the ultraviolet rays coming from the fixture.
Upper air units have been used in healthcare settings for decades and have been shown to be effective against airborne pathogens, reducing respiratory infections and sick days of workers.
Safety of UVC Upper Air Systems
When installed at or above the minimum mounting height of the unit, UVC exposure levels are kept below the ACGIH threshold limit value (TLV). This allows the fixtures to be operated continuously in occupied spaces.
Benefits of Upper Air UVC Fixtures
Compared to other solutions, including UVC HVAC, UVC air mover purifiers, and surface mounted air/surface fixtures with exposed lamps, upper air units have several distinct advantages.
Nearly silent operation. Compared to air purifiers that use fans to move air in room, upper air units take advantage of the natural convection of air current (warm air rises, cool air falls). This allows them to be simpler units with almost entirely silent operation.
Can be used in occupied times. When installed according to the manufacturer's instructions, upper air UVC fixtures are designed to prevent ultraviolet radiation from reaching harmful limits. This means they can be turned on and left operating continuously, allowing the UVC light bulbs to disinfect any air that enters the irradiation zone.
Easy to install where needed. With hardwired and plug-in options available, and simple mounting to walls (linear or corner) or ceilings (with pendant mounting), upper air UVC fixtures can be installed almost anywhere.
Testing UVC Exposure Safety
To test whether an upper air UVC fixture is emitting more UVC radiation than levels safe for human exposure, specialty UV meters or dosimeters can be used.
Dosimeters indicating 6mJ/cm2 can be placed around a room at heights where humans may be located. If the dosimeters change colors completely over the space of a few hours, the upper room fixture may need to be placed higher or further away, or the number of fixtures in the room be reduced. If the UVC dosimeters do not change color completely, then the level of germicidal irradiation is likely lower than the level dangerous for humans and the fixtures are appropriately sized and located.
UV light meters can be used around a room to indicate any UVC intensity at various distances and heights from the fixture. Various measurements around the room may indicate improper or damaged louvers in the upper air fixture are not directing UVC to the upper portion of the room. However, if the fixture is designed correctly, no or very low levels of UVC light should be measured around the room except very near the fixture itself. The UV light meter should show insignificant levels of intensity in zones the manufacturer indicates are safe.
