1. Air Pollution effects Acid rain Greenhouse effect Photochemical smog

2. Acid rain Acid rain is mainly causes by sulphur dioxide from burning of fossil fuel such as coal and oil When sulphur dioxide reaches the atmosphere, it oxidizes to first form a sulphate It then becomes sulphuric acid as it joins with hydrogen atoms in the air and falls back down to earth Acid rain occurs the most in heavily polluted air where other compounds such as ammonia and ozone help to catalyze the reaction, converting more sulphur dioxide to sulphuric acid.

3. Effect on tree and soil When sulphuric acid falls onto the earth as rain, nutrients present in the soils are washed away Aluminium present in the soil is also dissolved by the acid and this toxic element can be absorbed by the roots of trees Thus, the trees are starved to death as they are deprived of their vital nutrients such as calcium and magnesium

4. Effect on aquatic ecosystem Sulphuric acid (H2SO4) directly interferes with the fish's ability to take in oxygen, salt and nutrients needed to stay alive The heavy metals carried by the acid rain from the soil is harmful to the fist, Al+2 burns the gills of the fish and accumulates in their organs, causing much damage When the pH of the water is less than 4, the aquatic ecosystem will be totally destroyed

5. Effect on materials It attacks the stone surfaces of walls, statues and buildings.

6. Greenhouse Effect Carbon dioxide acts like a greenhouse by allowing radiant energy from the sun to enter, but absorbs a lot of the lower energy IR radiation. If the amount of carbon dioxide increase, more heat will be trapped, and the earth will be warmed up more This overheating problem is known as global warming.

7. Global Warming This affects our weather. This will melt the polar ice. This may cause flooding across huge areas of low lying land. Most of the reclaimed areas in Hong Kong would be flooded.

8. Photochemical smog It is formed in the atmosphere by the reaction between gaseous pollutants, nitrogen oxides and hydrocarbons in the presence of strong sunlight. Strong sunlight and calm conditions have higher potential to produce high levels of photochemical smog

9. In high concentrations photochemical smog can reduce visibility, irritate eyes and attack human respiratory system.