Does UV light kill mold? Yes, but that's an oversimplified answer. This article will discuss known facts about UV light and mold, how it affects mold, and if it is a reliable tool to eliminate mold in your home. Things rarely work out as people believe, so we're going to use facts and common sense so that you can use UV light correctly and get rid of mold where UV light stands out.
Each tool has its benefits and negatives; UV light, as we know and use it today, is no different. It has its place in killing mold in the home, but it's very specific applications where it's effective.
Let's dig into the facts, uses, and reliability of UV light in the home when used to kill mold.
What Is Ultraviolet Light?
Ultraviolet light is a type of electromagnetic radiation. We're all familiar with the x-rays we get at the dentist's office and the light that comes from the bulbs in our homes, but ultraviolet light is somewhere between the two. The wavelength of UV light is shorter than that of visible light but longer than that which is used for x-rays.
The electromagnetic spectrum that ultraviolet light is a part of is divided into 7 sections:
- Radio waves
- Microwaves
- Infrared
- Visible LIght
- Ultraviolet (UV)
- X-Rays
- Gamma-Rays
But, even UV light is subdivided 3 more times into:
- UVA
- UVB
- UVC
The only types we have to worry about when we're in the sun are UVA and UVB. When you're overexposed to UVB rays outside, you get a sunburn. But we're talking about killing mold with UVC from an artificial lamp.
Longwave (368nm)
Longwave UV is a naturally occurring part of sunlight and is the closest of UV light to visible light. This is used to create “blacklight blue” lights and is also a UV-A light. They can be designed and used in tanning beds to produce artificial sun tans.
Midwave (312nm)
This is also found in natural sunlight and is responsible for causing sunburns. It also activates the melanin in your skin and causes your skin to turn darker than normal. This is UV-B light.
Shortwave (254nm)
This is another wavelength of light that is found in natural sunlight, but it doesn't make it to the earth through the upper atmosphere. It's used in lights for mineral hunting because it can illuminate various fluorescent minerals. This is UV-C light.
How Does UV Light Kill Mold?
Mold is penetrated by UV light's short wavelengths of energy. Thus, it cleans and ultimately inactivates the DNA by breaking it up.
What Type of UV Light Kills Mold?
Direct exposure to UV-C light is necessary to effectively eliminate mold, bacteria, and mildew.
Disadvantages of Using UV Light to Kill Mold
The main disadvantage is a UV light in a room will not have enough intensity to kill the mold in a reasonable amount of time. Light also travels in a straight line, so corners, line of sight breaks, plus other factors make it ineffective when attempting to kill mold at a room level. It simply lacks the focused power to make a significant difference and cannot move around curves or edges in an average room, home, or business.
It is great when used to clean HVAC ducts because it's a closed area that keeps large quantities of UV-C light in a very small and condensed environment.
How Long Does It Take For UV Light To Kill Mold?
How long it takes depends on how much UV-C light you administer in any given location. In ducts, it takes seconds. You'll have more spores entering your home than it can deal with in an open room. The average UV-C machine for home use lacks the power and intensity to clean entire rooms.
Safety Considerations When Using UV Light To Kill Mold
UV-certified goggles and glasses are your friends, other than protecting your eyes, you should be 100% safe. Most home-based units have already taken care of these issues for you.
DIY vs Professional Services for Killing Mold with UV Light
for the DIY person, all you have access to are simple, consumer-based units that cannot do a thorough job. Specialized units to clean heating and AC ducts are completely different animals from consumer-based ones.
Conclusion
While you can kill some mold with the average UV-C machine, it's neither effective nor designed to be effective against prolific mold growth. Professionals pay top dollar for commercial machines. You would be much better off with a HEPA filtration system with a closed, sealed filter. It catches spores of .3 microns and larger, and that's most of them.
