A、dust B、dead human skin C、quill-coverts D、fluff B

Interviewer: Hello, everyone. Welcome to our programme Worldly Wise. Today our attention turns to pollution. We are lucky to have with us here our guest, Miss Catherine White, the youngest woman director of the Environmental Protection Agency. Go6d morning, Miss White.
Catherine: Good morning.
Interviewer: Well, Miss White, nowadays, most people believe it is the air outdoors that presents us, particularly those most sensitive to unhealthy air, with the greatest risk. But according to your group’s recent research, there seems to be something different.
Catherine: Yes, our research shows that it is not the air outdoors that takes us the risk. However, it is actually the air in- side our homos, schools, and other buildings that is most harmful.
Interviewer: Really?
Catherine: Really! According to a recent report made by my colleague, 50% of all illnesses is aggravated or caused by polluted indoor air. The indoor air is anywhere from 2 to 10 times more hazardous than the outdoor air. And the indoor air quality epidemic has become the nation’s number one environmental health problem.
Interviewer: Why is such a big problem not noticed before?
Catherine: Because it was not as serious as today. As a result of the energy crisis of the 1970s, with energy-efficiency in mind, today’s homes and buildings are built air-tight. Their air-tight construction keeps airborne pollutants trapped inside, and nature’s air-cleansing agents outside. Statistics for asthma problems began rising sharply around the same time that homes and buildings began to be built his way. In fact, a recent study found that the allergen level in super-insulated homes is 200% higher than it is in ordinary homes.
Interviewer: Besides the insulation of homes, is there anything else that worsens the indoor air?
Catherine: Yes, carpets, molds, mildews, fungi, dust mites, and many many others. A baby crawling on the floor inhales the equivalent of 4 cigarettes a day!
interviewer: But most people spend most of their time inside.
Catherine: Yeah. Some are over 90%. In this ease, the indoor air is going to affect our health far more than the outdoor air. Virtually everyone is affected, especially asthmatics and others who are particularly sensitive to allergens and dirty particles in the air. Keep in mind that no home or building is immune to the indoor air quality epidemic. 6 out of 10 homes and buildings are "sick".
interviewer: Sick? Do you mean the air in the house is in bad quality?
Catherine. Not only bad, but it is hazardous to your health. And even the Environmental Protection Agency’s very own headquarters, constructed a few years ago, was determined to be "sick". Many EPA employees could not work inside the building without becoming sick. If the headquarters of the EPA can fall victim to the indoor air quality epidemic, the very government agency that is charged with finding solutions to this problem, then any home or building can be afflicted. In fact, every home and building is affected by the indoor air quality epidemic to one degree or another, regardless of how clean it may appear.
Interviewer: But if my house looks really clean, how did it become that way?
Catherine: Did you use aerosols, floor or furniture polish, bleach, bathroom cleaners, etc.? If so, these products give off harmful chemical vapors into the air. Most homes or buildings also have carpets, painted walls, chemically-treated furnishings,  dust, insects, moist or damp things, food, people, and...
Interviewer: People?!
Catherine: Yes, humans shed more than just about any other animal, but our skin flakes are small enough to float in the air, and are consequently inhaled by anyone who enters a room. About 80% of what you see floating in a ray of sunshine is dead human skin ! This is not to mention other sources of airborne pollutants that we may bring indoors, such as cigarette smoke and pets. Even ff you eliminate or prohibit a certain source of indoor air pollution from your home, such as pets, you may still be affected.
Interviewer: So we’d better often stay outdoors.
Catherine: Maybe!
Interviewer: Thank you, Miss White. We have to stop here and next time she will give you some tips that can help you reduce the indoor pollution. Thanks for listening to our programme.