Ozone depletion

Ozone is a gas that occurs both at ground-level and in the Earth’s
upper atmosphere, known as the stratosphere. At ground level, ozone is a pollutant that
can harm human health. In the stratosphere, however, ozone forms a layer that protects
life on earth from the sun’s harmful ultraviolet (UV) rays. But this “good” ozone is
gradually being destroyed by man-made chemicals referred to as ozone-depleting
substances, including chlorofluorocarbons, hydrochlorofluorocarbons, and halons.
These substances were formerly used and sometimes still are used in coolants,
foaming agents, fire extinguishers, solvents, pesticides, and aerosol propellants.
Thinning of the protective ozone layer can cause increased amounts of UV radiation to
reach the Earth, which can lead to more cases of skin cancer, cataracts, and impaired
immune systems. UV can also damage sensitive crops, such as soybeans, and reduce
crop yields.