题目内容：

Asthma(哮喘) is a long-lasting breathing disease that affects millions of Americans, many of whom are children. People who get asthma will suffer from lack of breath, difficulty in breathing or coughing--which are caused by the tightening of the muscles in airways. Untreated asthma can lead to poor lung function and death, but asthma can also be effectively controlled with proper treatments.

Research is discovering  genes that contribute to the development of asthma. This development has pointed researchers to the role of indoor and outdoor pollution as environmental factors that contribute to the increased occurrence of asthma.

The Indoor Pollution

Indoor pollution has increased with the developments  in building materials and in heating and air conditioning systems. In addition to poisonous gases that come from paint, other materials like dust and perfumes used in household products such as washing powder are recycled continuously through the house, winter and summer.

Unlike the days before central heating or before whole-house air conditioning, these materials and chemicals cannot get out of modern homes. Most  often, they cause breathing  problems in the members of the family with the least-developed autoimmune(自身免疫的) systems. Proper venting (通风) and use of environmentally-friendly building materials and carpeting can help reduce the presence of these chemicals.

The Outdoor pollution

Researchers have also established outdoor pollution's role as a probable cause of asthma. Asthma has been proven

to result from some fuel products. Smog and the small matters carried by it have been recognized as a factor which leads to asthma since the 19th century when London saw more and more diseases in the industrial population. Industrial pollutants and other chemicals which are produced in water treatment and open treated water like that found in the swimming pools also contribute to increased cases of asthma as well as other illnesses.

Those most affected by the increase of industrial and environmental pollution are children. Although much has been done to control the levels of pollution in the US, there still remains much to do as it is a worldwide phenomenon. Until an international effort can be made to limit carbon emissions, the occurrence of environmental asthma will probably continue to increase.

The 1. between asthma and air pollution
The2. of asthma	● lack of breath ● difficulty in breathing ● coughing
The possible3. of untreated asthma	● poor lung function ● death
4. contributing to the increased asthma	Indoor pollution	●It is 5. by building materials and heating and air conditioning systems. ●6. some poisonous gases, dust and  perfumes worsen pollution. ●Some material and chemicals 7. in  modern homes.
Outdoor pollution	●Smog and the small matters carried by it cause asthma, which is proven by a(n) 8. number of lung diseases in the industrial population. ●Industrial pollutants and other chemicals in water are 9.to people’s health.
Conclusion	Only when all countries join together to limit carbon emissions can people be 10. from suffering environmental asthma.