Which one is better?
The ability to zap germs with a light instead of using toxic ingredients like bleach almost sounds too good to be true. So is it?
While the goal of germicidal UV and chemical disinfectant products is the same – to kill 99.999% of bacteria and germs that cause disease—their methods are a bit different.
Let’s break it down.
What is UV?
UV light has been used to ward off bacteria and other contagions since the 1800s. Modern-day applications to kill micro-organisms are already common in water treatment and the food, hotel and airline industries. But now with growing public health concerns over COVID-19, ultraviolet germicidal irradiation (UVGI), has received renewed interest.
In general, ultraviolet is a light that is invisible to the human eye. There are several types of UV radiation, however, UV-C (which has a wavelength between 200 and 280 nm) is short-wave radiation and is the one commonly used in disinfection and sterilization applications. The shorter wavelength, the more energy-rich, which gives it its potency to trigger a chemical reaction with organic molecules.
How do these methods work?
At the heart of any UVGI system lies a UV-C light source, which can include low-pressure mercury-vapor lamps or UV LEDs. When light is exposed to surfaces, UV-C radiation zaps microorganisms, destroying the DNA and RNA in the cells of pathogens so they can't replicate. The more Watts the UV lamp has, the more power and effect for disinfection or sterilization this lamp will have.
Disinfectants aren’t just your run of the mill soap and water. They’re chemical agents, such as ammonia, chlorine or alcohol. To be considered a disinfectant, it should technically be registered with the Environmental Protection Agency (EPA) (Here is a list of EPA- recommended disinfectants to combat COVID-19.) Much like UV-C, disinfectants destroy or damage the cells of pathogens like bacteria and viruses. However, it does so by interfering with their metabolism and is done after a surface is cleaned.
Both UV light and chemical cleaners prove to be very effective methods for disinfection. Most chemical disinfectants and UV light methods claim to be 99.999% effective against germs.
When looking at the efficacy of these two methods, it is important to consider proper use and the possibility of human error. While UV light methods can be used without much human intervention or elbow grease, chemical cleaning requires that the correct cleaning agent be used, the appropriate amount of agent is applied to kill the bacteria, and that no spots are missed on the surface. One study found that in hospitals, disinfectants were less than 50% effective on high-touch surfaces. Careful use is essential in order to reach the highest disinfection rates.
Use and Practicality
Between UVGI light and chemical cleaners, both air and hard surfaces can be kept clean. While chemical cleaners are mainly used to clean and disinfect hard surfaces, UV light can effectively kill microbes both on surfaces and in the air.
Your chosen cleaning method may depend on what time and resources you have available. While chemical cleaners are cheaper upfront, UV lights can ultimately lower labor and long-term cost. A study using pulsed UV for routine once-daily disinfection of hospital surfaces cut the number of housekeeping hours required in half, compared to using alcohol wipes in manual cleaning.
Both UV and chemical disinfection practices can help you clean within a matter of minutes. UVGI systems can disinfect a space’s air in about 10 minutes, with viruses reaching non-detectable levels after 20 minutes. Chemical disinfectants may take from 30 seconds to 10 minutes to work, depending on the pathogens present and chemicals used. Lysol, for example, recommends wetting a surface for 30 seconds then allowing it to air dry. To get rid of pathogens that are harder to kill, the surfaces should remain wet for even longer, sometimes up to 10 minutes.
UV disinfection systems are also energy-efficient and safe for the environment. Advancements in technology have spurred the production of smaller units from manufacturers such as PURO Lighting, which make devices that draw at 7 amps off of a standard 110V outlet. Hospitals, restaurants and other industries can easily employ these smaller systems. Due to a lack of volatile organic compounds (VOC) in UV disinfection compared to chemical substances, these systems spare the environment by removing the chance of harmful evaporation, mess, and runoff.
Obstacles and Side Effects
When comparing these two cleaning methods, it is important to consider human and environmental safety. Several studies have shown that chemical disinfectants such as bleach or glass cleaner can pose significant health risks, including triggering asthma or reduction in lung function, and even with some products, hormonal effects. Chemical cleaners also increase outdoor pollutions by contributing to smog formation.
Though safe for the environment, UV light can also pose some danger to humans. Exposure to the UV light is can harm skin and eyes, so UV cleaning systems cannot be used while a space is occupied.
Environments, with its trained consultants, can help with selecting the right approach that will result in the highest level of disinfection, protecting your customers, employees, and tenants.