Why is the ozone layer in the atmosphere considered good, and ozone at ground level considered a health risk?
High in the atmosphere, ozone provides a protective covering for the earth from the sun’s ultraviolet (UV) rays, which are harmful. However, ozone low to the ground is formed when certain chemicals and sunlight interact, and is the chief ingredient in smog. It is a strong irritant to the upper respiratory system and eyes, and can cause damage to crops.
