Does UV light Kill Mold and Mildew?

There's nothing more frustrating than having to deal with mold on a hot and humid day. While there are plenty of ways to prevent mold growth, UV light is a viable option to kill mold and mildew that many people have forgotten. In this guide, we will look at how does ultraviolet light works, what are the different types of germicidal UV light, and is it effective at eliminating mold. At the end of the post, we will recommend you the best UV appliances and should you buy one. Let's begin.
Short answer
UV-light is safe and effective against microorganisms.

Can Ultraviolet Light Really Kill Mold And Mildew?

UV-light is a proven technology that can kill mold, powdery mildew, germs, and other pathogens from spreading. Since the 18th century, it is widely used in industrial processes, medical equipment, and hospital e.g. surgical room. You can also find ultraviolet light used as microbial sterilization in water treatment, air purification, and food sanitization. A study conducted by Duke University Medical Center and University of North Carolina Health Care shows UV-light is able to reduce more than 91% pathogen in a hospital. The ultraviolet radiation will effectively sterilize airborne and surface biological pollutants that can’t be seen by our naked eyes. This is because mold spore, fungus, and other microorganisms are more vulnerable to the germicidal effects of a properly designed UV lamp. Just place the UVGI cleaners near a mold and mildew infested area that is typically moist, shaded with no sunlight coming through.

Dead mold spores can still cause allergic reactions and trigger asthma. Use natural ingredients like vinegar, baking soda, or hydrogen peroxide to clean and scrub off surface mold and mildew. Keeping room humidity between 30 to 50 percent is still the best solution to prevent mold and mildew growth. Consider mold remediation if the mold infestation has spread to cooling coils, drain pan, pipe, ductwork, and porous materials like ceiling, wall, wooden tiles. Using UV-light during the mold remediation process will create an extra layer of protection against mold spores that are disturbed. You will be at less risk of inhaling to airborne mold that may have spread across rooms via air ducts or HVAC.

How Does UV-light Kill Mold And Mildew?

UV-C short wavelength between 100 to 280 nanometers (nm) is responsible for disrupting the nuclei of mold and mildew thereby killing it. This is backed by many scientific studies confirming microorganisms vulnerability to UV-C short wavelengths. Ultraviolet (UV) is a form of electromagnetic radiation that can work as microbial decontamination. The germicidal light irradiates high-level electromagnetic energy that can penetrate into the nuclei acid and induces damage to the microorganisms’ DNA. By changing the arrangement of the molecules, the defected cell will cease to function. When the cell is disabled, mold and mildew cannot reproduce and it will eventually lead to death.

How Long Does It Take For UV Light To Kill Mold?

UV-C light with the wavelength between 200 to 280 nm will take one to two hours to kill 99.9% of the mold. Keep in mind there are limitations to ultraviolet light. Compact UVGI cleaners or UV air purifiers utilize a smaller UV-lamp that is typically less than 20 watt in power. The weaker light intensity will result in poorer UV radiation therefore less effective in sanitizing mold. The UV radiation effectiveness will also gradually decrease upon use thus it will take a longer time to destroy microbes. Some mold, mildew, and bacterial spores require higher UV exposure for disinfection so you will need to replace the bulb prior to depletion.

Another common reason is a dirty UV bulb. The chamber that holds the UV lamp might be coated in dust or debris after sometimes. This will reduce the UV-light disinfection performance as the dust contaminants are blocking the light from irradiating. Periodically cleaning and maintenance is needed to ensure the UV bulb is free from dust. Finally, the line of sight and placement will determine the UV-light sterilization effectiveness. First, consider the UV bulb size, power output, coverage, and types of technology applied. Next, ensure the ultraviolet germicidal irradiation (UVGI) or air purifier is placed within the mold source between 2 to 4 inches. If the UV light fails to irradiates and hitting the mold, the germicidal effects will have zero impact on existing mold and mildew.

Are Ultraviolet (UV) Light Safe for Human?

Ultraviolet light is safe and harmless for humans but not pathogens. The short wavelength of UV light will destroy mold and mildew DNA without producing any harmful chemicals. A complete contrast to mold-killing detergents like chlorine bleach, ammonia that will off-gas chemicals that are harmful to our health. Besides killing and preventing mold growth, the right doses of UV rays can even be beneficial to humans like improving mood and boost energy. Ultraviolet light is also used in skin therapy by stimulating the body to produce vitamin D. Vitamin D can help treat skin disorder, regulate calcium metabolism, insulin secretion, and blood pressure. However, overexposure to UV light can cause damage to the skin cell. Cumulative exposure may lead to premature wrinkles, sunburn, and increase the risk of skin cancer.

Max Fernandez

A loving father and a dedicated reviewer for airfuji.com with more than 1000 air purifiers under his belt. Max Fernandez is also one of the million patients currently suffering from asthma. Feel free to nudge him if you have any questions.