Those new lights: will they hurt you?

6. března 2013 v 3:55 |  street light
We're all switching to those new lights. Well, they're not so new. Compact fluorescents have been around for several years. Even light-emitting diode (LED) lighting, which is expensive but gaining popularity, is no longer novel. Both save lots of energy compared with the standard round lightbulb, ubiquitous for a century. But there are some things that you should know.

The standard bulbs are being forced out of existence by federal laws. Already, 100-watt lightbulbs can no longer be manufactured and sold in the US. By next year, the same fate will befall 75-watt lightbulbs.

First, remember that what appears as white light to the human eye is always a combination of red, green and blue light. If additional colors are present in the mix, the light still looks white. Now, because almost everything we see contains mixtures of light, the only way to know what is actually present in any light is to use a spectroscope.

This wonderful device unscrambles the mixture and reveals light's components. When a spectroscope is pointed toward the Sun, the Moon, any star or galaxy in the universe, a candle or old-fashioned round lightbulbs, it shows virtually the same thing. All these light sources are made of the spectral colors - all of them: the colors of a rainbow.

What a spectroscope does not show is that all natural sources also emit healthy doses of infrared. Though our eyes cannot see this, our skin senses it as heat. And thereby lies the problem. Ordinary lightbulbs produce more heat than light. This is not a problem in winter, when it helps warm the house. But in summer this energy is totally wasted. Indeed, a bunch of lightbulbs burning in July may be doubly wasteful, because then the air conditioner must work harder. Moreover, those bulbs emit "extra" colors like orange, yellow and violet.

Compact fluorescents, on the other hand, which glow by a process unseen in nature - the electrical excitation of mercury vapor - emit solely wavelengths of red, green and blue, with almost no infrared, which is why they are much cooler to the touch. They also emit no other colors. No wonder a mere 15 watts of power can create the same white light intensity as an old-fashioned 60-watt bulb. So if we really want to reduce our energy consumption, and not have to generate as much electricity - about half of which comes from burning filthy coal - forcing everyone to switch to fluorescent and LED lighting is a great idea.

There is one problem, however. The light, though it looks just as white as a standard lightbulb, is unnatural. Is this bad? Should this matter?

There is increasing evidence that ambient light affects health. For example, two independent epidemiological studies show that breast cancer is strongly correlated with women whose lifestyles prevent them from being exposed to nightly darkness. The mechanism appears to be blood levels of melatonin. Normally, melatonin serum levels are low by day and high by night. Exposure to visible light, including artificial light, suppresses the normal nocturnal production of melatonin by the pineal gland. In people who work night shifts, whose job or home location keeps them exposed to artificial illumination during the night, the body fails to gain normal melatonin levels. Bottom line: Get a night's sleep in a dark place. If you live in a bright city, close those shades and curtains.

So light does affect us, sometimes powerfully. And this brings us full circle back to the compact fluorescents and LED lighting. True, they save energy. But they bathe us and our children, who now are surrounded by this light at school and at home, with wavelengths that nature produces nowhere in the universe.

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