Pollution
adds additional molecules, including carbon dioxide and ozone, to the
lower parts of the atmosphere. While small amounts of both are natural
at ground level in the troposphere, their amounts have been increasing
because of the burning of fossil fuels. Carbon dioxide, a by-product
of the burning, is called a greenhouse gas because it contributes to
global warming. Ozone emitted in the troposphere damages plants and
causes respiratory problems, unlike the “good” ozone in
the stratosphere that protects the Earth from the Sun’s ultraviolet
light.
Larger particles of pollution in the lower atmosphere can also cause
respiratory problems. Though relatively small, ultrafine aerosols,
emitted by burning fossil fuels and possibly trees and other
vegetation, can
cause significant respiratory problems for some individuals.
Pollution
adds additional molecules, including carbon dioxide and ozone, to the
lower parts of the atmosphere. While small amounts of both are natural
at ground level in the troposphere, their amounts have been increasing
because of the burning of fossil fuels. Carbon dioxide, a by-product
of the burning, is called a greenhouse gas because it contributes to