【正确答案】大多数人都意识到了室外空气污染对健康有害，但是很多人却不清楚室内空气污染也会对健康产生严重的影响。研究表明，较之室外空气污染，室内空气污染程度或许要高出2～5倍，有时甚至100多倍。由于多数人大约90%的时间都在室内度过，室内空气污染的这种程度应当引起人们的特别关注。

【答案解析】[听力原文]
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. Studies indicate that indoor levels of pollutants may be 2～5 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.