UV light was first used for sterilization and disinfection in the mid-twentieth century. With technological advancements, particularly in UV bulbs, its dependable long lifespan (thousands of hours) and smaller size (e.g. UV LED vs traditional UV bulbs) have broadened the field for where it can be used. It is used to disinfect water, air, fruits and vegetables, surgical instruments, tablet computers, toys, and a variety of surfaces.
Not all types of UV light are effective for sterilization. What does this imply? To get technical, ultraviolet (UV) refers to a class of electromagnetic waves with a shorter wavelength (higher frequency and energy) than visible violet light. UV is classified into three types based on decreasing wavelengths and increasing energy.
UVA, UVB, and UVC are the three types of UV light. Only UVC (100-280nm) has enough energy to effectively destroy microorganisms in UV sterilization. When looking for a UV sterilization product to try in your home or business, make sure the UV wavelength is in the UVC range (100-280 nm).
What is the effectiveness of UV sterilization? Is it effective against bacteria and viruses? What are the advantages and disadvantages? These are common questions I hear as a microbiologist, especially when people consider how dirty their cell phone gets.
With so many UV sterilization products on the market, you may be wondering if they are worthwhile to try. Here’s a discussion to give you an idea of how UV sterilizers work:
UV Light and Doses
A UV dose is a collection of factors that determine how effective ultraviolet sterilization is. Transmittance is the amount of light that reaches the target; solids suspended in the water will prevent UV light from reaching the chamber’s edge and exposing all of the water. The flow rate is how quickly the water moves through the system; a faster flow rate reduces exposure time and thus effectiveness.
Turbidity measures how cloudy or clear the water is; high turbidity indicates that the UV light cannot reach the chamber’s edge and is only sterilizing the water closest to the lamp. Another factor is lamp age, as the UV intensity of the lamp decreases over time.
UV Sanitizer Design
UV sanitizers are intended to disinfect a variety of surfaces, including cell phones, jewelry, and stuffed animals. It is critical to remember that hand sanitizers should never be used (or the skin on any other part of your body, for that matter). According to the FDA, there have been reports of skin and eye burns caused by improper installation of UVC lamps in human-accessible rooms.
UV sanitizers come in a variety of forms, from wands to zip-up pouches, and can be used to sanitize a variety of items. A wand, for example, may be best for targeting household items like doorknobs, whereas a pouch may be best for fitting smaller items like a phone.
UV Sterilizer Longevity
Another factor to consider with personal UV sanitizers is that the energy emitted by their lights diminishes over time. It becomes less effective for its target as it decays, and I’m not sure how a person could tell how these bulbs are disintegrating. Although there is a ‘replace by’ date, most of us only replace a light bulb when it is completely out. This is far past the effective time of a UV source.
There’s also the possibility that using a personal UV sanitizer will cause more harm than good in the long run. They can be hazardous, especially if exposed repeatedly. Many microbes will naturally have some adaptation or resistance to UV light because they multiply and mutate so much faster than other types of organisms. This population of microbes will grow in your home over time, especially if exposed repeatedly.
UV Light Power
DNA and RNA are the genetic materials that make up all living organisms and control their growth, development, functioning, and reproduction. UV light emits electromagnetic energy, which can destroy microorganisms’ ability to reproduce and cause microbe inactivation through mutations and/or cell death.
UV light emits electromagnetic energy, which can destroy the ability of microorganisms to reproduce and cause photochemical reactions in nucleic acids (DNA & RNA). The ultraviolet energy causes the formation of specific thymine or cytosine dimers in DNA and uracil dimers in RNA, which causes microbes to become inactive by causing mutations, cell death, and failure to reproduce.
We first learned about UV-C light’s disinfectant properties (ultraviolet light with a wavelength of 200 to 280 nanometers — the same light that causes sunburn and skin cell mutation in humans).
Using a UV-light sterilization pouch or machine instead of soap and water can be more convenient. Reading this article should have given you a better understanding of how UV sterilizers work, as well as how to use them properly at home or outdoors.