The Ozone Layer in the Earth's atmosphere serves a very specific and very important purpose: it blocks most of the high-intensity ultraviolet light emanating from the Sun, which can cause burns and skin cancer in humans and animals. The ozone layer goes through periods of high and low density, and has been seen to be thinning due to pollution which breaks apart the ozone molecules. A highly-publicized thin area, or hole, in the ozone layer over Antarctica became the impetus for government regulation of many substances that are suspected of propagating into the atmosphere and thinning ozone. In areas where the ozone layer is thin, people are at risk of bad sunburns, as well as for higher incidence of melanoma and other skin cancers or conditions. Intense UV light can also cause damage to the eyes, leading to blindness if not tempered or treated. To avoid excess UV exposure, it is suggested that people wear sunblock, hats, and sunglasses when outside for long periods of time. As the thin areas of the ozone layer shift and move, different areas may become more or less affected by high UV exposure.