Let’s begin with a basic UV review. In addition to sunlight, UV light sources are found in the lab and shop. Sources include some biosafety cabinets, certain types of hand-held light sources, transilluminators, crosslinkers, and some laboratory instruments such as spectrophotometers. UV is a form of non-ionizing radiation found within the electromagnetic spectrum between X-rays and visible light and is generally divided into three classes based upon wavelength: UVA with a wavelength of 315 to 400nm(black light); UV-B with a wavelength from 280 to 314nm(erythermal) prevalent in sunlight and; UV-C with a wavelength from180 to 280nm(germicidal) such as the germicidal lamps found in biosafety cabinets and laminar flowhoods.

Sunlight is a major source of UV-A and UV-B. UV-C is almost never observed in nature because it is absorbed completely in the atmosphere before reaching the earth’s surface.

Hazards of UV do not distinguish between work and home, and the exposure guidelines for the general public for sun exposure are certainly applicable to the workplace as well. Exposure to sunlight can be a concern for those caring for large animals in outdoor locations and even those with responsibilities for exercising smaller animals outdoors. There is plenty of literature and general information on the use of protective clothing, sunscreens, and limiting exposure in middle of the day. The American Cancer Society¹ offers the guidance summarized below to help prevent skin cancer:

Cover up: Wear long pants and long sleeves when working in the sun. There are now good lightweight fabrics that are cool yet provide good UV protection.

Use a sunscreen with a sun protection factor (SPF) of 15 or higher: The SPF number only indicates the protection against UV-B rays. Sunscreens labeled as "broad-spectrum" protect against both UV-A and UV-B radiation, but there is no standard system for measuring protection from UV-A rays at this time. Products that contain avobenzone (Parsol 1789), ecamsule, zinc oxide, or titaniumdioxide are likely to offer some protection against most UV-A rays.

Be sure to apply the sunscreen properly: Always follow the label directions. Almost all sunscreens require re-application for effective protection throughout the day.

Wear a hat: A hat with at least a 2- to 3-inch brim all around is ideal because it protects areas often exposed to the sun, such as the neck, ears, eyes, forehead, nose, and scalp.

Wear sunglasses that block UV rays: Long hours in the sun without protecting your eyes increase your chances of developing eye disease. UV-blocking sunglasses can help protect your eyes from sun damage.

Limit direct sun exposure during midday: Another way to limit exposure to UV light is to avoid being outdoors in intense sunlight too long. UV rays are most intense during the middle of the day, usually between the hours of 10 A.M. and 4 P.M. If possible, schedule outdoor work in the early morning and late afternoon instead. Note: This can also help limit heat exposure.

Moving indoors,we do see accident reports resulting from non-sunlight UV exposures and that will be the focus of the remainder of our discussion. According to the Health Physics Society,²

“Accidental UV overexposure can injure unaware victims due to the fact UV is invisible and does not produce an immediate reaction…Reported UV accident scenarios often involve work near UV sources with protective coverings removed, cracked, or fallen off. Depending on the intensity of the UV source and length of exposure, an accident victim may end up with a lost-time injury even though totally unaware of the hazardous condition.”