Ultraviolet-C (UVC) light is a segment of the electromagnetic spectrum, and mold is a common fungus thriving in moist environments. This article explores how UVC light interacts with mold, its capabilities, limitations, safety measures, and common applications for mold control.
How UVC Light Affects Mold
UVC light damages living organisms, including mold, by disrupting their genetic material. This light, typically within the 200 to 280 nanometer (nm) wavelength range, is absorbed by the DNA and RNA within mold spores and cells. Wavelengths around 254 nm are highly effective for germicidal purposes. The absorbed energy causes changes, such as the formation of pyrimidine dimers, which prevents the mold from reproducing and growing, leading to its inactivation or death.
UVC Effectiveness and Practical Limits
UVC light is effective at eliminating mold spores and surface mold directly exposed to the light. However, it cannot penetrate porous materials like drywall, wood, or fabrics, meaning mold growing beneath these surfaces will not be affected.
UVC light also does not remove dead mold, which can still trigger allergic reactions or respiratory issues. Physical removal of mold remains necessary, even after UVC exposure. For UVC light to be effective, it requires a direct line-of-sight to the mold; shadowed areas or obstructions prevent inactivation. Therefore, UVC is a supplementary tool rather than a standalone solution for significant mold infestations.
Safety Measures for UVC Exposure
Direct exposure to UVC light is harmful to humans and pets. It can cause acute effects on the skin, similar to severe sunburn, including redness or ulceration. Prolonged or intense exposure also carries risks of premature skin aging and skin cancer.
The eyes are particularly vulnerable to UVC radiation, which can lead to photokeratitis, also known as “welder’s eye.” This painful inflammation of the cornea causes symptoms like a gritty sensation, eye pain, light sensitivity, and blurry vision, typically resolving within a few days. Long-term exposure may also contribute to cataracts or macular degeneration. Devices emitting UVC light should only be used in unoccupied spaces. Individuals who must be present should wear appropriate personal protective equipment (PPE), including UVC-blocking eyewear, face shields, gloves, and long-sleeved clothing.
Common Uses of UVC for Mold Control
UVC light is integrated into various systems for mold control, particularly as a preventive measure. It is commonly installed in Heating, Ventilation, and Air Conditioning (HVAC) systems. Here, UVC lamps are placed near components prone to moisture, such as cooling coils and drain pans, to inhibit mold growth and sterilize circulating air.
Air purifiers also frequently incorporate UVC technology to neutralize airborne mold spores and other pathogens. These devices draw air through the system, exposing it to UVC light before releasing it back into the environment. Additionally, UVC light is used for surface disinfection in unoccupied settings, such as laboratories, hospitals, or during professional mold remediation efforts after visible mold has been physically removed. These applications primarily aim to prevent growth or address airborne and surface mold, rather than eliminating deep-seated infestations.