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    According to the World Health Organization (WHO), environmental pollution kills 1.7 million children under the age of five every year worldwide. The WHO warns that child deaths will increase greatly if pollution continues to worsen. Of all the environmental problems, air pollution is being called the most dangerous.

    Most of these deaths take place in developing countries. However, WHO environment and health chief Maria Neira tells that air pollution is a leveler between rich and poor. Everybody, she says, needs to breathe.

    “You can be a very rich child, your parents very rich, but living in a place, in a city, which is very polluted. Then there is very little you can do because we all need to breathe. Air pollution is everywhere.”

    Maria Neira says one of the most important ways to reduce air pollution is to produce cleaner fuels for cooking and heating.

    “Almost half of the world population is using dirty fuels for cooking, heating, and lighting at home. And, this is affecting very much mothers who are staying and cooking at home, but the children who are around mothers—they are exposed as well.”

    Cleaning up how the world cooks, heats and lights homes and other buildings is a big-picture goal.

    But what can every one of us do to limit our family to air pollution?

    The U.S. Environmental Protection Agency has the following suggestions:

    ● Avoid walking where there is a high volume of vehicle traffic.

    ● Equip homes with air filters and air conditioning units.

    ● Limit your time outside if you live in an area that issues warnings about air quality.

    ● Wear high-grade, rated face masks tightly to the face when air quality is poor.

    ● If you live or commute in a very polluted area, remove your clothes and wash immediately after entering your house.

    However, the WHO stresses that governments around the world need to take the lead on ensuring that children grow up in a clean environment.

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    Imagine the situation. You are driving along a desert or on a mountain. You have no idea where you are. You passed the last house two hours ago. Then your car breaks down. It is night and it is cold. You have no mobile phone. What do you do? Well, next time take a GPS with you. This invention may be able to help you. It is a device(装置) which uses satellites (卫星) to find the user's position(位置). It can find your position to within 20 metres. A GPS cannot start your car, but at least you will know where you are.

    GPS, which means Global Positioning System, is a small radio receiver. It looks like a mobile phone. You can hold it in your hand, or put in your pocket. It is sometimes put into a watch or a telephone. We also find GPS devices in cars, planes, or boats. Some of these devices have electronic maps, so you know where you are. For example, in a city they can tell you the name of the street.

    There are three parts to the Global Positioning System. The first part is the receiver. You can hold it in your hand, or have it fixed into your car, plane, etc. The second part is a group of satellites orbiting the Earth. The receiver contacts at least four of the satellites and calculates(计算) its position. The third part of the system is a network of ground stations. They are all over the world. They control the satellites and make sure they are working well.

    Some people think that in the future the GPS will be as common as the mobile. They are becoming cheaper and more and more accurate(精确的). There are also new uses for the GPS. Perhaps they will become like watches. Everyone will have one and you will never be lost again.

    Many people know Shanghai's beautiful night view(景色), especially the colorful lights from the buildings. Light helps us see and makes the environment more beautiful. However, too much light becomes a kind of pollution but many of us pay little attention to this pollution or even ignore it. In fact, it causes a lot of problems. Light pollution can be almost as bad as carbon dioxide pollution.

    Too much light can do harm to our health. First, it can make us feel bad and we can't sleep well. Second, lights need electricity, and creating electricity will give off greenhouse gases. This affects the air and causes breathing problems. Third, study shows people living under bright light for long can have cancer more easily.

    Too much light may be even harmful to wild animals. Thousands of birds die from it each year. Some hit into the light buildings, because they can't see clearly in the strong light. Some birds sometimes lose their ways in the bright light Sea turtles(海龟) can't find the dark beaches to lay their eggs.

    To protect humans and wildlife, we should take measures to reduce the use of lights at night.