Steril-Aire, Inc., has announced that its germicidal ultraviolet C (UVC) light fixtures, which are designed to destroy harmful microbes circulating through HVAC systems, can help defend against the threat of infection from inhalation anthrax.

A NIOSH study performed in conjunction with

the University of Cincinnati found that UVC lights, on a single pass, destroyed more than 99 percent of four separate aerosolized bacteria. For decades, the Centers for Disease Control and Prevention has recommended UVC as part of an engineering control strategy to prevent the transmission of tuberculosis in health care facilities. The American Society of Heating, Air Conditioning and Refrigeration Engineers also has recognized the efficacy of germicidal UVC since 1982. Worldwide, UVC is used extensively to kill or inactivate microorganisms of all types.

Steril-Aire, which holds multiple patents for the development of HVAC-style UVC lights, reports a recent upsurge in business from facilities of all types concerned about bioterrorism. Installed in HVAC systems, the lights emit high-intensity ultraviolet-C energy to eradicate bacteria, mold, and viruses that grow in or circulate through these systems.

Forrest B. Fencl, president and CEO of Steril-Aire, offers these guidelines to potential users of the technology:

* Develop a multipronged HVAC strategy using air filtration, UVC, alarm/control devices, proper ventilation practices, and a "lockdown."

* UVC may be used in tandem with air filtration devices found in most buildings today An upgrade to higher-efficiency filters is advised only if the upgrade will not affect total airflow and therefore reduce the number of air changes in the building. It is important to maximize total airflow when trying to reduce concentrations of anthrax or any airborne particle, infectious or not.

* If a system already is equipped with HEPA or other high-efficiency filters, these devices will effectively trap most airborne bacteria, including anthrax, and prevent them from recirculating through the facility. The filters can, however, become a biohazard as a result. UVC lights installed upstream of certain filters can destroy microbes trapped inside to help prevent this problem.

* In a high-risk area within a high-profile building, consider shutting down accessible outdoor intakes on lower floors. Also consider placing locks on system access doors and changing of locks on mechanical rooms. Restrict entry into these areas to known people under escort. If return-air registers are accessible in any way, they should be guarded. If the building has automated system controls, configure an alarm to signal if tampering occurs with certain operations.

* In addition to destroying Bacillus anthracis, E. coli, Legionella, tuberculosis, and other infectious-disease organisms, UVC eliminates the organic contaminants that build up on the coil and in the drain pan areas--thereby improving the cleanliness and efficiency of HVAC systems. Most installations offer a rapid payback through resulting energy savings and reduced system maintenance.

UVC technology has existed for more than 70 years and is most frequently used outside the United States, primarily for water disinfection. The newer HVAC-style UVC lights, pioneered by SterilAire, deviate from conventional technology because they have been engineered to provide peak performance in cold- and moving-air environments.

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