How does ozone in the stratosphere protect human health?
Ozone molecules absorb most of the ultraviolet light that reaches the atmosphere from the sun. UV light, when it hits DNA in skin cells, produces mutations that can lead to the development of skin cancer. By absorbing most of the UV light, we are protected by the ozone from some of the damaging effects of UV light.
The ozone layer absorbs 97-99% of the sun’s high frequency ultraviolet light , light which is potentially damaging to life on earth. Every 1% decrease in the earths ozone shield is projected to increases the amount of UV light exposure to the lower atmosphere by 2%. Because this would cause more ozone to form in the lower atmosphere, it is uncertain how much of UV light would actually reach the earths surface. Recent UV measurements from around the northern hemisphere indicate small UV increases in rural areas and almost no increase in areas near large cities. http://www.nas.nasa.
