Ozone is the prime ingredient of smog in our cities and other areas of the country.
Though it occurs naturally in the stratosphere to provide a protective layer high above the earth, at ground-level it is the prime ingredient of smog. The average adult breathes 13,000 liters of air per day. Children breathe even more air per pound of body weight than adults. Because children's respiratory systems are still developing, they are more susceptible than adults to environmental threats. Ground-level ozone is a summertime problem.