According to Business Wire, in 2003: Ten percent of Americans spend on average $300 per year to tan indoors. This equates to a total US market for tanning of over $9 billion per year, and does not include the $3 billion tanning products market. Enhancements in technology and consumer acceptance are fueling the industry's growth. A suntan is the result of injury to the epidermis, the top layer of your skin.
the most striking example of fluorescence occurs when the absorbed radiation is in the ultraviolet region of the spectrum and thus invisible to the human eye while the emitted light is in the visible region which gives the fluorescent substance a distinct color that can only be seen when exposed to uv light
How they're made. Our eyes can detect only a tiny part of the electromagnetic spectrum, called visible light. This means that there's a great deal happening around us that we're simply not aware of, unless we have instruments to detect it. Light waves are given off by anything that's hot enough to glow. This is how light bulbs work - an electric current heats the lamp filament to around 3,000 degrees, and it glows white-hot. The surface of the Sun is around 5,600 degrees, and it gives off a great deal of light.