Air Pollution

Air pollution growing problem
For centuries, people have produced small amounts of pollution. For example, smoky fires have heated homes and blacksmiths’ forges for thousands of years. In the nineteenth century, pollution increased as people invented that produced pollution. Fuel-powered trains, ships and cars soon followed. During the twentieth century our use of machines increased, and human populations also grew. All this caused more pollution.
-Traffic pollution
As vehicles burn fuel, they give off poisonous gases including carbon monoxide and nitrous oxides. Carbon monoxide can harm your health, and even kill you, by preventing your body from absorbing enough oxygen. This can make you feel sleepy or give you a headache. Nitrous oxides also cause smog.
Exhaust fumes
Lead is sometimes added to petrol to make vehicle engines run smoothly. Lead from car exhausts can harm people’s kidneys, brain and nervous system. In developed countries, such as those in North America and in Europe, cars now run on lead-free petrol, which causes less pollution. They are also fitted with devices called catalytic converters that clean up exhaust fumes. But every year there are more and more cars on the road, so car pollution is still a big problem.
-Smog
Smog forms when waste gases from car exhausts react with sunlight to produce a gas called ozone. High in the air, ozone can be helpful, but near the ground it builds up to produce a foul-smelling haze. Smog is a major problem in cities such as Los Angeles and Mexico City, which lie in bowl-shaped valleys that trap the dirty air.
Health problems
Air poisoned with smog may harm our health. It can make our eyes and throat sore, and cause allergic reactions. Some people, including many children, suffer from asthma and other breathing problems. In certain cities the problem is so bad that people sometimes have to stay indoors or wear a mask.

2009-12-05 21:45:38 補充：
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Air pollution in hk will be from car and power station.
1 use public transport like mtr and bus while reduce to use private car

2 promote the 環保意識,use less energy, eg dont leave the machine in standby mode.

3introduce new mode car which emit less exhause gas, eg introduce electric car

It means the air is dirty. If you don't breathe too much, you are helping to reduce the CO2 in air.