Do you want to know if ultraviolet light will actually kill mold?
UV radiation has been in use for years by hospitals to disinfect operating rooms and medical equipment.
In this guide, I will be going over...
- How UV light kills and prevents mold growth
- The different types of germicidal UV light products to kill mold
- Why I always recommend installing a UV light in your HVAC system
Let's get started with this guide!
Will UV Light Actually Kill Mold?
Under the right conditions and with a properly designed product, germicidal UV light can be effective in killing mold --- and preventing it from taking root. UV light has been in use for many years as a disinfecting technology to not only kill mold, but also bacteria, viruses, and other pathogens.
In fact, as early as 1878, Arthur Downes wrote a scientific paper describing the sterilization of bacteria to short-wavelength light.
Ultraviolet light acts very similarly to humans getting a sunburn. Sunburns are caused by longer wavelength light, but the principle is very much the same.
Mold and other microbes have far less protection against the germicidal effects of light than humans.
The UV-C Short Wavelength
Scientists have discovered that there is a certain wavelength range where microorganisms are vulnerable to damage --- and this is the UV-C short wavelength range --- specifically in the 100 to 280 nanometer range.
Ultraviolet light is used in different industries for microbial decontamination such as in hospitals, water treatment, air purification, and food sanitization.
There have been numerous scientific studies showing that UV-C is effective in killing microogranisms. The short wavelength known as UV-C is responsible for disrupting the nuclei of microorganisms --- which either kills it or prevents it from reproduction.
How Does UV Light Kill Mold?
Ultraviolet irradiation works as a disinfectant and uses electromagnetic waves to penetrate through organisms.
The wavelengths are of various sizes --- between 255 and 280nm --- known as the Germicidal UV-C that kills microorganisms. The ultraviolet light irradiates the immediate environment in which it is placed such as in an indoor air conditioner.
And when the germicidal rays come across molds, they penetrate into the nuclei of the molds, damaging the nucleic acids present --- until their the organism becomes disabled.
According to the research work found in the US National Library of Medicine on Light-Based Anti-Infectives, it was reported that the disinfectant mechanisms of UV light cause actual damage to DNA by changing the arrangement of the molecules.
When the DNA "arrangement" is changed, it causes defects in the cell reproduction of the mold and it will eventually lead to cell death --- when the cells die, the mold dies.
Read Also: 7 Pictures Of Mold In Air Ducts
What Are The Best Conditions For UV Light To Kill Mold?
The effectiveness of UV light in killing mold depends on multiple factors, and some of the most important things are...
#1. Light Intensity
If the UV light is very weak, then it won't be nearly as effective.
Most UV lights installed in HVAC systems have light bulbs in the 8-watt to 16-watt power range.
In fact, these lights are so powerful that they even have sight glasses (peep holes) so you can verify the UV light is on without directly looking at it. At this level of intensity, exposure can damage your eyes and skin.
#2. Line of Sight
In order for UV light to work in killing mold, there has to be line-of-site.
If the mold is growing behind an object, and UV light isn't directly hitting the mold, then the germicidal effects of the light will be largely non-existent.
The light has to actually reach the mold for it to have any type of effect.
This is one reason why you never see mold growing in direct sunlight. Natural sunlight has a weak germicidal effect on microbes.
#3. UV Lamp Debris
If the UV light bulb is coated in dust or debris, it can also greatly lower its reach. This is why periodically cleaning the UV bulb or replacement is so crucial.
A dirty UV bulb can halve the sanitizing power of a new & clean bulb.
Read Also: How To Install An HVAC UV Light?
What Are The Different Types of Mold-Killing UV Lights?
Since ultraviolet light can be so effective in disinfection of environments, different types of products are available to homeowners in order to kill and prevent mold.
HVAC UV Lights
Perhaps the most common germicidal UV product is the HVAC UV Sanitizer.
These custom UV lights are installed inside of your indoor air handler, furnace, or heat pump. Usually composed of one or two UV bulbs, these UV lights are normally on 24-hours a day inside of your air handler --- killing microbes and mold.
There are even more premium models that will turn on automatically based on whether the A/C or heat has actually turned on.
This feature can significantly lengthen the life of the ultraviolet light bulb (one of the biggest ongoing expenses is changing the bulbs yearly).
Read Also: 7 Pictures Of Mold In Air Ducts
UV Light Water Sterilizer
There are also UV products designed to purify the entire homes water supply.
These systems will kill microbes, germs, and pathogens that are in your water supply that either the municipal system misses or because you are on well water and need disinfection.
These whole water purification systems are installed at the main water supply, usually installed immediately after the main water shutoff.
Portable UV Disinfection Lamps
Another increasingly popular product is the portable disinfection lamp.
These products are designed to be very small and portable and can be used to quickly disinfect pillows, faucets, door knobs, and other small objects. Some of these portable lamps will turn off automatically if it is held upright in order to prevent damage to your eyes.
What's The Bottom Line On UV Light Killing Mold?
UV light can be highly effective in killing and controlling mold in either an HVAC system, water supply, or even for food.
Hospitals, food processing centers, and water treatment facilities have been using germicidal UV light for years, and I'm sure UV will continue to be used to sterilize a variety of objects.