A group of researchers in the USA have been working on a simple strategy that has the potential to slow the spread of harmful micro-organisms, such as the flu, from busy public spaces.
A team of physicists from Columbia University Medical Center found that a subtype of ultraviolet light called UVC had the potential to eliminate disease-causing micro-organisms, such as the flu, without harming humans. Ultraviolet (UV) light is universally used by hospitals and science laboratories to destroy bacteria and viruses. It acts by breaking down DNA and proteins. The problem is that UV light can only be used when there are no people around or with protection because UV light can penetrate the skin and eyes. Too much exposure to UV light can eventually cause serious health issues, such as cancer and cataracts.
UVC Light is Less Harmful to Health
So, what makes UVC so special? UV light can be divided into three subtypes: UVA, UVB, and UVC. UVC has a shorter wavelength than the more commonly known UVB and UVA subtypes. These three subtypes differ not only in wavelength but also in their biological activities and ability to penetrate human skin. What the team at Columbia University Medical Center found was that in addition to its known ability to destroy microbes, UVC is not able to penetrate the outer layers of human skin or eyes, unlike UVA and UVB.
Eliminating Bacteria and Viruses using UVC Light
The team used a series of progressive experiments to demonstrate that UVC can eliminate bacteria present on surfaces and airborne flu viruses. The latter experiment was performed by exposing flu aerosols to either nothing (the control) or to a specific wavelength of UVC (222 nanometers) in a closed chamber. The resulting liquid samples were collected and added to cells that were susceptible to the flu virus. The team found that flu aerosols exposed to UVC could not infect the cells whereas the flu aerosols that were not exposed to UVC could induce flu in the cells. This suggests, as reported in a recent article of Science Health, that there is a strong possibility that a tool using UVC could be developed to help slow, or even eliminate, the spread of disease in crowded public spaces, such as airports, schools, and hospitals. Public spaces, particularly those that experience a high volume of people, are notorious for spreading disease. Therefore, a tool such as this would be invaluable.
Fortunately, technology already exists that could help to translate these findings into reality. This comes in the form of excimer lamps, which are used in LASIK eye surgery. The team has demonstrated that they can create a concentrated beam of UVC light at 222 nm by using filters to remove all other wavelengths. Currently, excimer lamps cost approximately $1000 (US dollars), but the team expects that this price could come down substantially if they can prove that the technology works and if the lamps are mass produced.
This research is, however, still in preliminary stages. More studies must be conducted to determine whether UVC is limited to certain bacteria or viruses, such as the flu, and to establish doses of UVC that are both safe and effective. There are also concerns that these lamps will not be able to target surfaces contaminated with microbes and may have a limited impact on aerosols because they are likely to be positioned near the ceiling. Despite this, the team is hoping to be in a position that they can gain regulatory approval in the not-too-distant future.
Written by Natasha Tetlow, PhD
(1) Cohen J. Could ultraviolet lamps slow the spread of flu? Science Health. 2017. Available at: doi:10.1126/science.aas9109.
(2) UV radiation: What is the difference between UVA, UVB and UVC? Available at: www.who.int/uv/faq/whatisuv/en/index2.html