When infrared laser pointers hit the mass market, all sorts of concerns erupted. Bogus information began to circulate claiming serious health risks from exposure to infrared light. Infrared light, though, poses relatively few dangers to humans who employ common sense.
The astronomer William Herschel discovered infrared light in an 1800 experiment with a glass prism. He split sunlight into its spectrum, or rainbow of visible light, and measured the temperature of each colour. Herschel discovered an invisible region of the spectrum just beyond red that possessed thermal energy, making it warmer than the other colours. This became known as infrared.
Infrared light occurs naturally in the physical world, primarily in sunlight. Scientists have not uncovered any evidence that exposure to naturally occurring infrared light poses a health risk. However, infrared light can pose dangers in certain applications.
According to NASA scientists, infrared light takes two forms: near infrared and far infrared. Far infrared light provides the heat from sunlight and fire. Far infrared light has long wavelengths, about the size of a pinhead. Near infrared light has shorter, microscopic wavelengths, much closer to those of visible light.
Far infrared light is thermal. In other words, it produces heat. The heat you feel after spending time in the sun is an example of far infrared light, as well as the heat that radiates from wood stoves and gas heaters. Infrared lamps at fast-food restaurants keep foods warm. Many other devices in today's world, including TV remote controls, also operate via infrared light.
Some people believe infrared light causes cancer. The real culprit is ultraviolet (UV) light, at the opposite end of the electromagnetic spectrum. Scientists have discovered that UV light, which destroys cells, can cause skin cancer.
Some applications for infrared light actually save lives. Infrared light can penetrate smoke, clouds and dust. This makes night searches for lost individuals and criminals possible. Firefighters now use infrared cameras to find individuals trapped in burning homes. Infrared also has applications in most fields of science, and in the military.
While general exposure to infrared light poses no known health risks, the infrared light used in saunas generates extreme heat. This can cause overheating and dehydration. In addition, laser pointers concentrate infrared light into a narrow beam. Under extreme circumstances, this light can pose dangers to the human eye.
According to DrGreene.com, lasers fall into four categories. Class 1 lasers are relatively harmless. Class 2 and Class 3 lasers are used for pointers, and must carry a warning cautioning individuals to avoid shining them into any person's eye. A 1997 article in the medical journal Ophthalmology concluded that Class 3 lasers pose harm to the eyes only when the beam is directed on the same spot for 10 seconds or more. Class 4 lasers pose greater danger, but aren't used in laser pointers. Instead, their use is limited to military, medical and industrial applications.