FRITZI BODENHEIMER:

This is SCIENCE IN THE NEWS in VOA Special English. I'm Fritzi Bodenheimer.

FAITH LAPIDUS:

And I'm Faith Lapidus. Winter conditions are affecting many countries in Earth's northern hemisphere. Winter brings cold weather and, with it, a danger as old as man's knowledge of fire. The danger is death or injury by carbon monoxide poisoning. Today, we tell about this ancient and continuing danger.

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FRITZI BODENHEIMER:

Several years ago, a family was enjoying a holiday in the American state of California, near the Pacific Ocean. The family included five children and their parents. The oldest child was 12 years old. The youngest was three.

The family was spending the weekend in acamper. A camper is a small shelter carried in the back of a truck. People can sleep in it for a few days.

The weather turned cold the second night the family stayed along the Pacific coast. The camper did not have any heating equipment to warm the space while family members slept.

FAITH LAPIDUS:

Someone decided to heat the area by placing a charcoal grill inside the camper. The device burned a wood product, charcoal. The fire immediately warmed the family members. They all went to sleep.

The next day, other people found the family. The parents and their five children had died in their sleep. They died because they did not know that burning wood products creates a deadly gas – carbon monoxide.

Carbon monoxide poisoning is known as a silent killer. The California family went to sleep in their warm camper and never woke up.

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FRITZI BODENHEIMER:

Carbon monoxide poisoning causes death and injuries around the world. The poison gas has been a problem since people first began burning fuels to cook food or to create heat.

This gas is a problem in all parts of the world that experience cold weather. A few years ago, America's Centers for Disease Control studied deaths linked to carbon monoxide poisoning. It found that the average number of carbon monoxide deaths in the United States was greatest in the month of January.

The C.D.C. also found that carbon monoxide kills more than 400 Americans each year. And, it said, more than 20,000 people are taken to hospital emergency rooms for treatment of health problems linked to the gas.

FAITH LAPIDUS:

Carbon monoxide is called the silent killer because people do not know it is in the air. The gas has no color. It has no taste. It has no smell. It does not cause burning eyes. And it does not cause people to cough.

Yet, carbon monoxide gas is very deadly. It steals the body's ability to use oxygen.

Carbon monoxide decreases the ability of the blood to carry oxygen to body tissues. It does this by linking with the blood. When the gas links with the blood, the blood is no longer able to carry oxygen to the tissues that need it. Damage to the body can begin very quickly from large amounts of carbon monoxide.

How quickly this can happen depends on the length of time a person is breathing the gas and the amount of the gas he or she breathes in.

FRITZI BODENHEIMER:

Carbon monoxide poisoning has warning signs. But people have to be awake to recognize them. Small amounts of the gas will cause a person's head to hurt. He or she may begin to feel tired. The victim's stomach may feel sick. The room may appear to be turning around. The person may have trouble thinking clearly.

People develop severe head pain as the amount of gas continues to enter their blood. They will begin to feel very tired and sleepy. They may have terrible stomach pains.

FAITH LAPIDUS:

Carbon monoxide is measured in parts per million in a normal atmosphere. Breathing in 200 parts per million of carbon monoxide will cause the first signs of poisoning. It will result in head pain, stomach problems and a feeling of tiredness after two to three hours.

A level of 800 parts per million will cause a person to lose consciousness. Victims will not know what is taking place around them. This will happen within two hours of breathing in this amount of carbon monoxide. Twelve thousand parts per million of the gas will cause death in one to three minutes.

FRITZI BODENHEIMER:

Medical experts say carbon monoxide affects people differently. For example, a small child will experience health problems or die much quicker than an adult will. The general health of the person or his or her age can also be important.

An older adult with health problems may suffer the effects of carbon monoxide more quickly than a younger person with no health problems. People with heart disease may suffer chest pains. They may begin to have trouble breathing.

FAITH LAPIDUS:

Carbon monoxide does not always cause death. But it can cause many medical problems. Breathing low amounts of the gas for long periods of time can lead to permanent damage in the heart, lungs or brain.

Medical experts say small amounts of carbon monoxide over a long period of time can greatly harm an unborn baby.

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FRITZI BODENHEIMER:

What causes carbon monoxide gas? Any device that burns fuels such as coal, oil or wood can create the gas.

Water heaters that burn natural gas create carbon monoxide. Fireplaces and stoves that burn wood create the gas. Natural gas stoves and gas dryers or charcoal grills also create carbon monoxide. Automobiles create it. Any device that burns fuels like coal, gasoline, kerosene, oil or wood will produce carbon monoxide.

Experts agree that the leading cause of carbon monoxide poisoning is damaged equipment that burns these fossil fuels. They say many people die or are injured by the gas because they do not use these devices correctly.

Experts say any device used to heat a home should be inspected to make sure it is working correctly. And, no cooking equipment like a charcoal grill should ever be used to heat an inside area.

FAITH LAPIDUS:

Carbon monoxide gas is created by fuel burning devices because not all of the fuel is burned.

Most devices used for home heating have a way to expel the gas from the home. For example, a fireplace has a chimney. Natural gas stoves or gas water heaters are usually connected to a device that safely expels the gas from the home. An automobile has a system for releasing unburned gasoline under and behind the vehicle.

Anyone who uses a device that burns fossil fuel must inspect the equipment carefully to reduce chances of carbon monoxide escaping. Companies that produce the devices usually provide directions about using the device correctly. These directions should be read and understood before using any equipment that burns fuel inside a home.

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FRITZI BODENHEIMER:

You can do a number of things to protect yourself from the effects of carbon monoxide. First, immediately leave the area if you recognize the signs of carbon monoxide poisoning in yourself or others.

Seek emergency medical services after you leave the area where you suspect the gas might be. Usually the treatment for carbon monoxide poisoning involves breathing in large amounts of oxygen. However, a doctor will know the best method to treat the effects of such poisoning.

Carbon monoxide does not quickly leave the body, even after treatment has begun. It can take several hours before the gas disappears.

FAITH LAPIDUS:

If you suspect carbon monoxide is a problem in your home, you might call your local fire department. Many firefighters have the necessary equipment to find or identify the gas.

In many countries, it is possible to buy and use a special device that will warn when harmful levels of carbon monoxide are in the area. These devices can be linked to a home's electric system. Others are battery-powered. Experts say these devices should be placed near sleeping areas in the home.

The most important weapon against carbon monoxide poisoning is the safe use of materials to heat any enclosed area. Safety directions that come with heating equipment must be followed. Older equipment powered by fossil fuels should be inspected every year to make sure it continues to be safe. Knowledge about the dangers of carbon monoxide could be the most important information you ever learn.

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FRITZI BODENHEIMER:

This SCIENCE IN THE NEWS was written by Nancy Steinbach. Our producer was Brianna Blake. I'm Fritzi Bodenheimer.

FAITH LAPIDUS:

And I'm Faith Lapidus. Join us again next week for more news about science in Special English on the Voice of America.

camper: a recreational vehicle equipped for camping out while traveling 露营车

charcoal grill:烤架

kerosene: a thin oil distilled from petroleum or shale oil, used as a fuel for heating and cooking, in lamps, and as a denaturant for alcohol 煤油

fossil fuel: fuel such as coal or oil, that was formed over millions of years from the remains of animals or plants 矿物燃料（如煤或石油）

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(来源：VOA 编辑：陈丹妮）