EPA Report on Indoor Air Quality


Ultra-Violet Lights

The US Environmental Protection Agency published a report on September 6, 2006 entitled, “Biological Inactivation Efficiency of HVAC In-Duct Ultraviolet Light Devices”. The EPA was concerned with terrorists introducing biological warfare agents (BWAs) into heating, ventilation, and air conditioning (HVAC) of target structures to distribute pathogenic organisms. The introduction of BWAs into a building’s HVAC system could harm many people, depending on the size of the building. This potential threat indicates a need to identify and test devices that could be used to destroy BWAs as they move through a building’s air handling system.

One category of technology that may meet this need uses a configuration of ultraviolet (UV) lights that can be deployed inside the building’s air ducts. Short-wave ultraviolet radiation in the “C” band (UV-C) has wavelengths of 200 to 280 nanometers. This type of ultraviolet germicidal irradiation (UVGI) has been used for over 100 years to inactivate microorganisms.

In the test nine UVC devices were evaluated and designed to be mounted inside an HVAC system to inactivate bio aerosols as they migrate through the air handling system. The devices were tested separately in a laboratory-based test duct with state-of-the-art aerosol and microbiological generation and measurement equipment.

The testing was conducted using one spore-forming bacteria, Bacillus atrophaeus (B. atrophaeus), one vegetative bacteria, Serratia marcescens (S. marcescens), and one virus, Escherichia coliphage MS2 (MS2 bacteriophage). The structural characteristics and susceptibility to UVC inactivation make these reasonable surrogates for BWAs.

Performance and Results

All nine UVC devices were ≥ 99 percent efficient at inactivating the vegetative bacteria.

Three UVC devices were ≥ 93 percent effective for all three microorganisms.

Five devices had ≤ 46 percent efficiency for inactivation of the spore form of the bacteria

Two devices had ≤ 46 percent efficiency in destroying the virus.

The following table shows the airborne inactivation efficiencies of each device for each test organism. See the EPA URL below for full results