The atmosphere is polluted by
gases that humans produce (cars, industries etc).
- The fumes
produced during combustions consist of microparticles that are
dispersed into the air. These fumes are responsible for the blackening
of the facades of buildings and their degradation.
- Acid rains
form after releases to air of nitrogen oxides and sulfur oxides. These
rains are harmful to vegetation and can destroy entire forests. They
can also damage some building materials (marble, iron, aluminum, zinc).
The limitation of emissions of sulfur oxides and nitrogen oxides has
helped reduce this phenomenon.
- Destruction of the ozone layer is caused by chlorinated compounds
released into the air. The ozone layer has regularly regressed: its
thickness decreases and even tends to disappear completely at the poles.
amplification of greenhouse effect leads to a general increase in
The greenhouse effect is a natural phenomenon necessary to maintain
temperatures favorable for life on Earth but the rejection of some
gases (mainly carbon dioxide and methane) amplifies it.
If this rise of
temperatures continues it will be responsible for dramatic changes.
This change may:
- favors the expansion of arid areas
- multiplies extreme weather events such as cyclones
- changes vegetation
- causes a rise in sea level making disappear many coastal areas and
- rises acidity of oceans and make disappear many marine species.