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 fungi growth, UV light is a viable option to kill mold and mildew that many people have forgotten. In this guide, we will look into how ultraviolet light works, the different types of germicidal UV light, and its effectiveness against mold. At the end of the post, we will recommend you the best UV air purifier that should you buy. Let's begin.
Short answer
UV-light kills mold, mildew, and other microorganisms.


Can Ultraviolet Light Kill Mold And Mildew?

Similar to the power of sunlight, ultraviolet radiation can kill biological pollutants like mold, powdery mildew, germs, bacteria, viruses in the air and surface area. A scientific study conducted by Duke University Medical Center and University of North Carolina Health Care shows UV-light is able to reduce more than 91% of pathogens in a hospital.

Mold spores and other microorganisms are vulnerable to the germicidal effects of a properly designed UV lamp. A proven technology that exists since the 18th century, UV light is widely used in meat processing, industrial processes, underground basement, healthcare center, and hospitals e.g. surgical room. You can also find UV light used as microbial sterilization in water treatment, medical equipment, air purification, and food sanitization.

The benefit of ultraviolet light is it kills mold and other microbes without releasing chemical byproducts. According to U.S. Environmental Protection Agency (EPA), it is a recommended solution over chlorine bleach that off-gasses harmful toxins with adverse health effects when inhaled.

How Does UV-light Kill Mold And Mildew?

UV-C light uses short wavelength in the range of 100 to 280 nanometers (nm) to inactivate and kill mold, mildew, bacteria, viruses. 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 will not trigger an allergic reaction.

How Long Does UV Light Take To Kill Mold?

In general, UV-C light takes 1 to 2 hours to kill 99.9% of the mold. However, the exposure time will vary depending on the UV light intensity and the proximity of the mold. You will also need to factor in the cooling effect of airflow, the strain of the mold in resisting UV irradiation, the types, and the coated material of the light bulb.

To ensure the ultraviolet light runs at maximum efficiency, turn off all light sources in the room including doors and windows. Replace the light bulb prior to depletion as the UV radiation effectiveness will gradually decrease upon use. The weaker the light intensity, the longer UV exposure it takes to destroy the mold and microbes. Regularly cleaning is needed to keep the UV light bulb dust-free. A dirty UV bulb or chamber will reduce the sterilization performance as the dust is blocking the ultraviolet light from irradiating. Lastly, place the UVGI air cleaners near a mold and infested area that is typically moist, shaded with no sunlight coming through. If the UV light fails to hit the mold, the germicidal effects will have zero impact.

Are Ultraviolet Light Safe for Human?

UV-C light is safe for humans because it has a limited range that cannot penetrate through the outer cell of human skin or the tear layer in the eye. It will emit ozone byproducts but at an insignificant concentration level. However, long-term exposure can still damage the skin cell resulting in premature wrinkles, sunburn, acute photokeratitis, and skin cancer. UVC light can kill pathogens like bacteria and viruses because it is much smaller than human cells. A complete contrast to mold-killing detergents like chlorine bleach, ammonia that will off-gas harmful chemicals.

Besides killing and preventing mold growth, the right doses of UV rays can improve mood and boost energy levels. Ultraviolet light is also used in skin therapy by stimulating the body to produce vitamin D. Vitamin D can help treat skin disorders, regulate calcium metabolism, insulin secretion, and blood pressure.

The Alternate Ways Of Dealing With Mold

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

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.
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