ASHRAE Journal - August 2008 - (Page 28)

Ultraviolet Germicidal Irradiation U The U.S. General Services Administration requires that UVC be included in cooling coil air-handling units for all new facilities and alteration projects to maintain coil cleanliness and improve air quality. Current Best Practices ltraviolet germicidal irradiation (UVGI) is the use of ultraviolet (UV) energy (electromagnetic radiation with a wavelength shorter than that of visible By Stephen B. Martin, Jr., Member ASHRAE; Chuck Dunn, Member ASHRAE; James D. Freihaut, Member ASHRAE; William P Bahnﬂeth, Fellow ASHRAE; Josephine Lau, Student Member ASHRAE; and Ana Nedeljkovic-Davidovic, . Student Member ASHRAE including smallpox and lupus.3 During the 1930s and early 1940s, researchers experimented with UVGI to control the spread of contagious airborne diseases. In 1936, Hart successfully used UVGI to disinfect air in a Duke University hospital operating room by showing a reduction in surgical wound infections.4 A landmark study during the measles epidemic of 1941 – 1942 showed a signiﬁcant reduction in infection among Philadelphia school children in classrooms where UVGI systems were installed, compared to control classrooms without UVGI.5 The success of these early studies provided hope that UVGI could be useful in preventing the spread of disease. Yet, successful outcomes were countered by studies showing that UVGI had little or no effect. Through much of the 1940s and 1950s, interest in UVGI applications was low. Then, in the late 1950s, Riley and O’Grady successfully used UVGI to August 2008 light) to kill or inactivate viral, bacterial, and fungal species. The UV spectrum is commonly divided into UVA (wavelengths of 400 nm to 315 nm), UVB (315 nm to 280 nm), and UVC (280 nm to 200 nm). The entire UV spectrum can kill or inactivate many microorganisms, but UVC energy provides the most germicidal effect, with 265 nm being the optimum wavelength.1 Modern UV lamps primarily create UVC energy at a near-optimal 254 nm by electrical discharge through lowpressure gas (including mercury vapor) enclosed in a quartz tube. UVC from mercury lamps is sometimes referred to as UVGI to denote its germicidal properties. Although UVC is invisible to the human eye, small amounts of energy released at visible wavelengths 28 ASHRAE Journal produce the blue glow commonly associated with UVC lamps. Brief History UVGI was ﬁrst demonstrated to disinfect water in 1877.2 In 1903, Danish physician Neils Finsen was awarded the Nobel Prize in Medicine and Physiology for his research using UV radiation for the treatment of various diseases, ashrae.org http://ashrae.org

Table of Contents Feed for the Digital Edition of ASHRAE Journal - August 2008

ASHRAE Journal - August 2008 Contents Commentary Industry News Letters Meetings and Shows Maintain to Sustain—Delivering ASHRAE’s Sustainability Promise Ultraviolet Germicidal Irradiation: Current Best Practices Improving Humidity Control With Energy Recovery Ventilation Single- or Two-Stage Compression Data Center Cooling: Using Wet-Bulb Economizers Building Sciences InfoCenter Practical Pointers Products Emerging Technologies Washington Report People Special Products Classified Advertising Advertising Index

ASHRAE Journal - August 2008

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.