The environment is everything around us - the air, ground, water, plants and animals. It is the place we live in, so it is very important to look after it. If we look after the environment, the environment will look after us.

Unfortunately, motor vehicles like cars, vans and lorries aren't very good for the environment. Their engines work by burning petrol, and this gives off poisonous fumes - you'll have seen them coming out of exhaust pipes and probably smelt them when a car has just been started. Although these fumes may not seem too bad at first, they're actually doing a lot of damage to the Earth.

The fumes are made up of gases like carbon dioxide. We are releasing too much carbon dioxide into the atmosphere, and it's slowly causing the temperature all over the Earth to rise. The effect of this global warming is very harmful to the environment and everything in it, including us. When we breathe in car fumes from the air around us, they damage our lungs and can cause diseases such as asthma.

About 200,000 tonnes of carbon dioxide are released into the atmosphere in Britain every year just by cars taking children to school. That means that if just 1 in 20 of those children cycled or walked with their parents instead, carbon dioxide pollution would be reduced by 10,000 tonnes per year. It's as simple as that!

So, if we all rode bikes, there would be less air pollution, the environment would be a healthier place and so would we!

What other advantages are there? Go to Roads to find out.