The Effects of Fluorescent Lighting on the Eye

Fluorescent lighting has been around since the early 1900's, though it wasn't until the mid-1900's when bulbs were made available on a commercial scale. Fluorescent bulbs are considered a more efficient use of heat energy and can last 10 times longer than incandescent light sources. Their effects on the human eye may be less beneficial than their effects on the environment.

Fluorescent Lighting

• Fluorescent lights work by combining electricity, argon gas and mercury inside a glass tube. Moving electrons are made to excite the gas which causes the gas to generate ultraviolet light. The ultraviolet light then reacts with the mercury to create visible light. Light is generated along an electrode that runs through the glass tubing allowing electrons to travel from one end of the tube to the other. In effect, light that comes from a fluorescent bulb is made up of green, blue and violet light waves that travel in pulses, or flickers of 120 cycles per second.

Electrical Pulses

• The electrical pulses generated by fluorescent lighting--while economical overall--may have adverse effects on the eyes. The eyes receive and process light through wavelengths. Each wavelength of light is received by a photoreceptor within the eye, so each wave that hits the eye is processed by a photoreceptor. Electrical pulses, as opposed to a steady stream of light, require the eyes to work harder. This coupled with the blue, green and violet colors used in fluorescent lighting makes the eyes work even harder, since these colors travel in shorter, more frequent wavelengths than colors within the red portion of the spectrum.

Headaches

• The electronic pulses generated by fluorescent lights are not visible to the human eye, however, the eyes may still be affected by pulsating wavelengths. Fluorescent lighting has been associated with physical ailments like headaches, migraines and eye strain. Researchers A. J. Wilkins and I. Nimmo-Smith conducted a study in 1989 to examine these effects. The results were reported in an article in "Lighting Research and Technology, Volume 21." In the study, one floor of an office building was supplied with fluorescent lighting that generated a slower pulse effect while another floor used a newer, fast-pulsed fluorescent lighting. After a one month period, workers were surveyed on any physical discomforts experienced. Researchers found the workers subjected to the newer fluorescent lights had a 50 percent drop in complaints of headaches than those who worked under the slower pulsed lights.

Types of Ballasts

• The newer model fluorescents used in the above study were designed to generate pulses at a much faster rate than the older model bulbs. Inside each bulb is a component called a ballast. The ballast is responsible for exciting the argon gas inside the tube. This makes for a stronger electrical discharge when electrons encounter the gas. Newer model fluorescents use an electronic ballast, whereas older model bulbs use a magnetic ballast. It's the ballast that causes the pulsing of the light. Electronic ballasts work faster thereby reducing the flicker effect of the light. The faster pulse appears more like a steady stream of light than the slower pulsed waves. Long fluorescent tubes typically use a magnetic ballast while the short spiral bulbs use electronic ballasts.

Migraines

• The same pulsing effect that sets off headaches may also play a part in triggering migraines in people who are prone to them. As each photoreceptor in the eye works to process incoming pulses, these cellular processes generate wastes or by-products, like the skin generates sweat when the body is exerted. These by-products can build-up under an excessive workload leaving cellular processes little time to eliminate them. As each person's biochemistry is different, slow elimination processes can result in eye strain. In the case of migraine sufferers, flashes of light can be a pain trigger. Multiple, minute flashes of light may have the same effect.