2. Air pollution is the contamination for release of gaseous substances, liquid or solid that will alter the natural composition. The primary factors of this pollution are the exhaust gases from cars and power energy.

3. The main pollution substances are: sulphur oxide; nitrogen oxide; lead and benzene; carbon monoxide; carbon dioxide.

4. Smog is a kind of air pollution that occurs in shapes similar to fog or haze in the lower layers of the atmosphere, usually in conditions of calm wind and thermal inversions at low quotas. It helps to increase the greenhouse effect and maintains the occurrence of acid rain.

5. Carbon dioxide is emitted mainly by combustion processes, particularly the discharges of motor vehicles with a hydrocarbon, except methane, and causes the increase of greenhouse effect. The sulphur dioxide causes acid rain.

6. Air pollution can irritate the eyes, throat and lungs. Burning eyes, coughing and a feeling of oppression in the chest disorders are frequent when you are exposed to high levels of air pollution. Lead and other heavy materials are toxic and often carcinogenic. People with diseases of the heart or lungs can be very sensitive to exposure to air pollution. Children most often suffer diseases such as bronchitis and asthma in areas where the air is more polluted than those in which it is cleaner.

7. Trails of condensation cloudy stripes are at the beginning thin, later, they expand to form wide ribbons that extend laterally. They are generated by the passage of airplanes and they are produced by condensation and solidification of the water vapor. Chemical trails tend to persist longer, enlarging slowly instead of disappearing.

8. The emission of pollution substances in the atmosphere can be reduced through special technologies: a first solution may be to turn to alternative sources of energy such as solar and wind power; to diesel fuel and to gasoline may be preferred gas LPG and natural gas, that develop much less carbon monoxide;

9. dust emitted from industrial installations can be filtered and retained by special purifiers; it is also necessary to reduce all the waste of energy; to improve air quality, it is necessary that everyone agrees not to use the car when the journey can be covered by public transport, walking and cycling.

10. Credits Presentation arranged by Andrea Baldi & Andrea Corradini – Itis “Pascal” – Cesena –Italy (2008-009) Thanks to the teachers: A.M. Ravazzi (Biology) – A. Tortora (English) and to the Technical Assistant: F. Fiori Pictures: www.sciencephoto.com www.sciencephoto.com E810389-Industrial_air_pollution-SPL.jpg A510144-Fireball_from_liquid_petroleum_gas_explosion-SPL.jpg Liquid_nitrogen-SPL.jpg E100257-Global_warming-SPL.jpg E812154-Trees_killed_by_acid_rain_and_other_pollution-SPL.jpg E810367-Air_pollution-SPL.jpg E810470-Woman_wearing_a_face_mask-SPL.jpg T610396-Aeroplane_contrail-SPL.jpg T146638-Wind_turbines,_California,_USA-SPL.jpg P930400-Cyclist-SPL.