Studies examining light sources in our indoor environment suggest that indoor lights emit an unexpected amount of ultraviolet light as measured by a spectral radiometer. Several studies indicate that commonly used indoor lamps, including halogen, incandescent and fluorescent lamps, emit significant levels of UV rays. Although the dose is very low, the exposure time is relatively long, which can cause significant cumulative damage. This is particularly worrying in patients who are exposed on a daily basis, which doesn't give the skin enough time to recover.
Although threshold doses have been determined for patients with normal skin, they have not been determined for patients with lupus. Until these studies are done, it will continue to be difficult to know how best to counsel photosensitive patients. Therefore, the safest thing for these patients is to use bulbs that emit the lowest levels of UV rays with a glass wrap or filter. I've read that everything from fire to LEDs can produce UV radiation.
In general, unless otherwise intended, the bulbs will have a phosphor coating to prevent UV radiation from escaping from the bulb. Although technically this creates a light source that emits a low amount of UV rays, it is possible to create raw, unfiltered light that doesn't emit ultraviolet radiation. Indoor lighting is also implicated in the worsening of melasma and other photosensitive dermatoses. Incandescent bulbs have little or no UV irradiation.
However, fluorescent lighting has been shown to increase lifetime UV exposure by 3% depending on the distance between the lamp and the skin. If the lamp is close (especially the desk, bed and ceiling), the light and heat emitted can worsen photoexacerbated dermatitis. Avoiding close contact with light or adding acrylic or plastic diffusers to light can help reduce exposure. Light-emitting diodes (LEDs) generate light from a semiconductor material; the color of the light depends on the material of the lamp.
LEDs do not emit UV rays and, therefore, are a safer source of light for the skin. The long fluorescent tubes used in home and office light fixtures produce very little UV light. In general, the hotter the filament, the more UV rays it will produce, although most incandescent bulbs are designed to minimize UV rays. Chronic exposure to ambient light can darken the skin, so daily protection against UV rays is necessary both indoors and outdoors.
Therefore, it is important to understand what doses of UV rays are capable of causing damage and to appreciate the cumulative effects of chronic exposure to low doses of UV rays. Older cathode ray tube displays emit UV radiation; however, newer liquid crystal (LCD) or flat panel displays, which are typically found on laptops, desktop computers, and mobile devices, don't emit UV radiation.
