UVC diodes are an irradiation source and require due precautions to ensure safe usage. This page contains information intended to familiarize users with the current understanding of some of the general practices and precautions most often recommended in the literature for UV irradiation sources (further information is provided in this application note). It is not meant as an exhaustive review on the topic. Currently, there are no work place related rules and regulations that are set by OSHA (Occupational Safety and Health Association) in regards to UVC environmental health and safety.

UV Light and Health Effects


The UV range of the electromagnetic radiation spectrum extends from 10 nm to 400 nm. Depending on the wavelength and time of exposure, UV radiation may cause harm to the eyes and skin.
 



The UV spectrum is separated into four parts: UVA (315 nm to 400 nm), UVB (280 nm to 315 nm), UVC (200 nm to 280 nm) and UV Vacuum (100 nm to 200 nm). Decreasing wavelengths correspond with higher frequency radiation and a higher amount of energy per photon. 

Biological Effect of UV Light


UVB has often been noted for its harmful effects on human skin, however each of the UV bands—UVA, UVB and UVC—have a potential for damage. Adverse health effects that may occur include erythema, photokeratitis, retinal burn, cataracts and others.

The shorter UVC wavelengths are typically absorbed in atmosphere, as shown in Figure 2, and thus are thought to have less long-term damaging effects on human tissue. However, in rare instances, prolonged direct exposure to UVC light has caused eye and skin damage. Because of this, exposure precautions are recommended when using UVC light. 




UVC Effect on Skin


Acute (short-term) effects include redness or ulceration of the skin. At high levels of exposure, these burns can be serious. For chronic (long-term) exposures, there is also a cumulative risk, which depends on the amount of exposure during your lifetime. The long-term risk for large cumulative exposure includes premature aging of the skin and skin cancer.

UVC Effect on Eyes


Eyes are also susceptible to UV damage. Even a few minutes’ exposure to the UVC radiation can result in photokeratisis (an inflammation of the cornea) and conjunctivitis (inflammation of the conjunctiva). Both the conditions are painful but not permanent.

Personal Protective Equipment (PPE)


UV radiation is easily absorbed by clothing, plastic or glass. Once absorbed, UV radiation is no longer active. When working with open UV radiation during maintenance, service or other situations, personal protective equipment covering all exposed areas is recommended. When working around UVC devices, employees should:

  • Use UV goggles and/or full face shields.
  • Prescription glasses and normal safety glasses do not protect eyes from UV exposure, so ANSI Z87 rated eyeglasses with wrap around lens to protect the side exposure is recommended. Consult with ANSI Z87 manufacturers for proper UV exposure protection equipment.
  • Cover any exposed skin using lab coats, nitrile gloves or other lab attire.

Safety Design/Control/Monitoring/Maintenance


UVC exposure can be reduced through product safety design considerations and controls. For example, safety switches wired in series allow UVC sources to be turned off without exposing workers to UV light. Or placing ON/OFF switches for UVC light sources separate from general room lighting in locations only accessible by authorized persons. Switch locations should be locked or password protected to ensure that the UVC source is not accidentally turned on. Each UVC system should have the option of a viewport so workers can view the lamp assembly without the possibility of over-exposure to UVC. 

Proper installation, monitoring, education of maintenance personnel, signage and use of safety switches can help to avoid overexposure. The operating instructions and recommendations for proper use of any UV system should be kept for reference to reduce hazardous exposure. These should be clearly visible for the operators or maintenance personnel and include the temperature and relative humidity ranges specified by the system design to ensure safe operation. Maintenance should be performed according to manufacturer’s instructions electric power should always be turned off to prevent accidental exposure. There are no standard guidelines for monitoring UV equipment, but there are commercial UV monitors that detect output or leakage. 

Response to UV Exposure


The effects of acute exposure to UV radiation are usually not severe and many symptoms are delayed. In the event of UV exposure, the following actions are recommended.

  • See an ophthalmologist if eye damage is suspected.
  • Treat skin lesions immediately.
  • Follow your organization’s EHS incident reporting procedure. These often require documentation of the date and time of incident, persons involved, equipment involved and type of injury

Further Questions?


If you have further questions about UVC LEDs and how they can be integrated into your product(s), please contact Crystal IS today.