If you've been sunburned, you know firsthand about the harmful effects of ultraviolet (UV) light. The UV-A and UV-B ranges of ultraviolet light are what make you sunburn.
Well, here's something you probably didn't know (I didn't until recently): other wavelengths of ultraviolet (UV) light are germicidal! Certain wavelengths in the UV-C range neutralize flu viruses, along with other viruses, bacteria, and other pathogens (fungi, molds, etc.).
In fact, UV-C light is routinely used to treat air, work surfaces, and equipment in hospitals and laboratories in order to reduce the risk of infection. It's also used to treat water. And it's used for sterilization in pharmaceutical manufacturing and food processing facilities.
How UV-C neutralizes pathogens
UV-C light doesn't destroy the virus or other microorganism. Rather, it sterilizes it - which is good enough for our needs, if you recall how a virus causes sickness.
Certain wavelengths of UV-C light damage the DNA or RNA of viruses, bacteria, and other pathogens. Since DNA and RNA carry genetic information necessary for reproduction, the UV-treated microorganisms lose the ability to multiply and cause disease.
(For the technically curious: UV-C light damages the nucleic acid of microorganisms by forming covalent bonds between certain adjacent bases in the DNA. Such bonds prevent the DNA from being unzipped for replication. [Source])
As with all of your pandemic planning,
Regarding possible residential uses for disinfectants (of any sort), don't just think "keep my household from getting sick." What if someone in your household has, in fact, gotten sick with pandemic flu? Then you not only know that (1) the virus is, in fact, within the four walls of your residence, but (2) the virus is reproducing and being given off by the sick person.
Advantages of UV-C as a germicide
- Ultraviolet light is a non-chemical approach to disinfection. It is simple, inexpensive, and requires very low maintenance.
- Because ultraviolet light works by physically damaging the DNA, viruses and other germs cannot develop resistance or immunity to it. Microorganisms will remain susceptible to UV-C light.
- It makes your environment healthier in general. Regardless of whether a flu pandemic occurs, UV-C lamps will always provide the benefit of disabling all kinds of viruses, bacteria, fungi, and molds.
Using UV-C light against flu viruses
Using ultraviolet light as a germicide simply involves exposing the flu virus to an appropriate amount of UV-C light.
Note: We're NOT talking about an air filter which traps contaminants. Rather, it's an air sterilization or purification system - a germicide. It doesn't remove the viruses, bacteria, and other pathogens. Rather, it renders them incapable of reproducing. (Again, that's fine for our needs.)
Since flu viruses can spread by contact on surfaces or by air (and perhaps other ways), there are different types of UV-based sanitizer lamps:
- For central heating and air conditioning systems, a UV-C lamp mounts inside the air duct. The UV light treats the air flowing through the duct.
- Freestanding units can be placed anywhere and plugged into an AC electrical outlet. The unit contains the UV-C lamp and a fan which circulates room air through the unit's UV-C light chamber.
- Ceiling units are mounted high on the wall and shine UV-C horizontally in a shallow zone just beneath the ceiling. As convective air currents circulate air up to the ceiling level and back down, airborne microorganisms are carried through the UV-C light.
- Hand-held units can be used to sterilize specific surfaces, objects, water (in a glass), etc. Possible uses: kitchen and bathroom countertops, utensils, doorknobs, telephones.
- Specialty units are used for industrial-sized facilities, mail sterilization, medical equipment sterilization, and other applications.
Bear in mind: the UV-C light must shine on the microorganisms in order to neutralize them. So while the light can disinfect smooth surfaces (e.g., dental tools), it cannot reach all microorganisms on porous surfaces or materials. Also, microorganisms can be shielded in small cracks and other shaded areas. As a result, UV-C lamps should be used in concert with other disinfectants and sterilization techniques.
Understanding germicidal UV
Ultraviolet germicidal irradiation (UVGI) explained
What microorganisms are deactivated by ultraviolet light?
List of companies providing Ultraviolet Germicidal Irradiation products (see subhead "UVGI Systems")
History of UV-C sanitization
The ultraviolet component of sunlight is a main reason microbes die in the outdoor air.
Based on that knowledge, ultraviolet germicidal irradiation became widely used after World War II. It was an effective way to disinfect without using either chemicals or high temperatures.
Later, with the increased availability of antibiotics and new disinfecting agents, the use of UV-C as a germicidal declined. However, as bacteria became resistant to antibiotics and as other side-effects and limitations to chemical disinfectants emerged, UV-C regained popularity.
The Science of UV-C light
All light is measured in wavelengths - ranging from ultraviolet (UV) ... through the visible colors (violet to red) ... to infrared light. (Humans cannot see ultraviolet or infrared light.)
Ultraviolet light is classified into three wavelength ranges:
- UV-C, from 100 to 280 nanometers (nm)
- UV-B, from 280 to 315 nm
- UV-A, from 315 to 400 nm
Within the UV-C range, sterilization lights usually generate a wavelength of 254 nanometers (or 254 billionths of a meter), which is especially effective against microorganisms.
UV lamps look and operate much like fluorescent lamps. In both, UV radiation is emitted from ionized mercury vapor. The difference is that the fluorescent lamp bulb is coated with phosphorous, which converts the UV radiation to visible light. The UV lamp is not coated, so the UV light can shine onto the lamp's surroundings.
Sanitization: Other products
Hand sanitizer - An alcohol-based gel or foam. Used by itself. No water required. Comes in a pump bottle for bathroom, kitchen, nursery, classroom, etc. and in small tubes for pocket or purse (especially valuable when no soap and water is near). Available at many drug stores; or order in any quantity from Medical Supply Group or Drugstore.com.
Nose sanitizer - Sounds crazy until you remember your nose is a MAIN point of entry for germs. Think about the air in crowded subways, airplanes, classrooms, events, etc. Not alcohol-based like hand sanitizers; uses pharmaceutical grade ethyl alcohol, natural ingredients, and virucidal plant-based compounds. Long-acting. Only available directly from the manufacturer, Nozin (i.e., not available in drug stores).