Most people are aware that outdoor air pollution can damage their health，but many do not know that indoor air pollution can also have significant health effects.Environmental Protection Agency studies indicate that indoor levels of pollutants may be 3～5 times，and occasionally more than 100 times，higher than outdoor levels.These levels of indoor air pollutants may be of particular concern because most people spend about 90% of their time indoors.
There are many sources of indoor air pollution in any home.These include sources such as oil，gas，coal，wood，and tobacco products，building materials，wet or damp carpet，and furniture made of certain pressed wood products，products for household cleaning and maintenance，personal care，or hobbies，central heating and cooling systems.
Immediate effects may show up after a single exposure (暴露) or repeated exposures.These include irritation of the eyes，nose，and throat，headaches，dizziness.Such immediate effects are usually shortterm and treatable.Sometimes the treatment is simply removing the person’s exposure to the source of the pollution，if it can be identified.
The likelihood of immediate reactions to indoor air pollutants depends on several factors.Age and preexisting medical conditions are two important influences.In other cases，whether a person reacts to a pollutant depends on individual sensitivity，which varies tremendously from person to person.Some people can bee sensitized to biological pollutants after repeated exposures，and it appears that some people can bee sensitized to chemical pollutants as well.
Certain immediate effects are similar to those from colds or other viral (病毒性的) diseases，so it is often difficult to determine if the symptoms are a result of exposure to indoor air pollution.While pollutants monly found in indoor air are responsible for many harmful effects，there is considerable uncertainty about what concentrations or periods of exposure are necessary to produce specific health problems.People also react very differently to exposure to indoor air pollutants.Therefore，further research is needed to better understand the effects of indoor air pollution and to find efficient ways to protect our health.
【小题1】According to the first paragraph，which of the following is NOT true?A．People often fail to notice indoor air pollution.B．Indoor air pollution sometimes is more dangerous than outdoor air pollution.C．Outdoor air pollution may not be so serious as indoor air pollution.D．It is obvious that people have been paying more attention to indoor air pollution.【小题2】According to the author，which may NOT be the source of indoor air pollution?A．Building materials.B．Wet carpet.C．Cooling system.D．Refrigerators.【小题3】What does the underlined word “irritation” in the third paragraph probably mean?A．Bad intention.B．Much sensitivity.C．Injury.D．Carelessness.【小题4】Which of the following might be the best title for the passage?A．Reactions of PollutionB．Danger from HomeC．Pollution ResourcesD．Different PollutionsD
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(答案→)D
解析：
【小题1】 D
解析 细节理解题。由第一段第一句可知，A项正确，D项错误；由第一段后两句可知B、C两项正确。
【小题2】D
解析 细节理解题。解题范围在第二段，本段内容提到了A、B、C三项内容，未涉及D项。
【小题3】 B
解析 词义猜测题。结合该词所在的语境可知，该词是指一种不良的反应或是病症，再结合第四段第三句中的individual sensitivity“个体敏感度”可知，该词是指过敏反应。
【小题4】 B
解析 标题归纳题。本文主要讲室内污染，即家里存在的健康隐患，所以B项最贴切。