Building Technologies

Using Light to Fight Bacteria and Viruses

27 June 2018

UVGI system sterilizing water using UV-C light generated from low pressure mercury discharge lamps. Source: ProMinent UVGI system sterilizing water using UV-C light generated from low pressure mercury discharge lamps. Source: ProMinent

The ultraviolet germicidal irradiation (UVGI) market is predicted to grow to $430 million by 2023, almost tripling in size in a decade. Much of this growth is attributed to air disinfectant systems with the upper-room systems sub-segment showing the fastest growth. Hospitals, food and beverage packagers, and workplaces in general are looking to UVGI as a means of reducing or eliminating microorganism contamination. UVGI can be used to disinfect air, water and surfaces, although surface disinfection is limited by microshadows and absorptive layers.

Contamination of air by microbial pollutants has increasingly been identified as a public health issue. In an effort to reduce building-related illnesses, UVGI is being used to combat bioaerosols such as bacteria, viruses and fungi. These microorganisms, often contained in droplets in the air, can cause allergies and the spread of diseases. People sensitive to these microbial pollutants complain of a wide variety of symptoms including fatigue, nausea, headaches, congestion and eye irritation.

UVGI uses short-wavelength ultraviolet (UV-C) light to kill or inactivate microorganisms by destroying their nucleic acids and disrupting their DNA, leaving them unable to perform vital cellular functions. UV-C light, primarily at 254 nm, is used because it corresponds to the energy of pyrimidine dimers in nucleobases. Specifically, the absorption of a photon forms pyrimidine dimers between adjacent thymine bases in the microbe’s DNA, rendering it incapable of replicating, or, in high dose cases, killing it.

As early as 1890, Robert Koch demonstrated the lethal effects of sunlight on tubercle bacillus, foreshadowing the modern use of UVGI to combat tuberculosis (TB) infection outbreaks. For the next half-century, scientists continued to show that UV, specifically UV-C, could be used to combat bacteria in fluids. In 1935, William F. Wells demonstrated the ability of UVGI to combat airborne microbes.

Despite these early successes, the rise of antibiotics combined with vaccination programs reduced interest in UVGI systems. Since the mechanism involved wasn’t fully understood until the 1960s, misconceptions, as well as fear at its possible effects on humans, kept the technology dormant for several decades. A resurgence of drug-resistant strains of TB in the 1980s led to renewed interest in UVGI. Since then, there has been a gradual improvement in UVGI technology up to today.

As it turns out, the UV-C wavelengths used in UVGI systems are much less dangerous to humans than feared. In fact, UV-C is much safer than other forms of UV radiation such as UV-A or UV-B because most of UV-C is absorbed by the outer dead layer of human skin. The less energetic UV-A and UV-B radiation tend to penetrate deeper. This can be seen in their effects, with UV-B responsible for sunburns and UV-A responsible for skin aging (photoaging).

Direct exposure to UV-C is to be avoided when possible. Exposure to unprotected UVGI instruments has been shown to result in skin irritation and eye discomfort. The U.S. National Institute for Occupational Safety and Health recommends that exposure to UVGI (254 nm) be less than 6,000 microJ/cm2 over a daily eight-hour period on unprotected skin or eyes. This is the reason why ceiling units are one of the fastest growing sub-segments. These units are removed from room occupants and minimize exposure.

Today, UVGI is used in a variety of applications including food, air and water purification. UVGI devices produce strong enough UVC light in circulating air or water systems to make them inhospitable environments to microbes such as bacteria, viruses and molds. UVGI can be coupled with a filtration system to sanitize air and water.

With increasing instances of antibiotic-resistant bacteria and the unfortunate anti-vaccination movement, UVGI is needed once again to minimize infection and help combat outbreaks. Early studies of the technology in hospitals showed that it significantly reduced the risk of infection after operations. UVGI should not be mistaken as a panacea; at best it can mitigate these issues. However, it will save lives, which is why the market for these instruments is growing so quickly.



Powered by CR4, the Engineering Community

Discussion – 1 comment

By posting a comment you confirm that you have read and accept our Posting Rules and Terms of Use.
Re: Using Light to Fight Bacteria and Viruses
#1
2018-Jun-27 4:59 PM

Far-UV Sterilray lamps are mercury free, so no hazardous waste disposal to worry about.
Visit https://sterilray.com to learn more.

Engineering Newsletter Signup
Get the GlobalSpec
Stay up to date on:
Features the top stories, latest news, charts, insights and more on the end-to-end electronics value chain.
Advertisement
Weekly Newsletter
Get news, research, and analysis
on the Electronics industry in your
inbox every week - for FREE
Sign up for our FREE eNewsletter
Advertisement
Find Free Electronics Datasheets
Advertisement