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根据材料请回答Pollution around the HouseScientists are closely concerned with the structure of buildings and with the quality of building materials.The World Health Organization (WHO) observes that the introduction of air conditioning and energy conservation measures have been accompanied by growing problems of indoor air quality.Some pollutants(污染物)arise from insulation(绝缘)products, some from moving cars, and others from modern housing materials.As many Europeans spend up to 900% of their lives in buildings, the health effects of the indoor climate are very important.
Some construction materials, including fiberboard, insulation foams and certain glues(for man-made wood floor boards, for example), gives out organic products such as form-aldehyde(甲醛).Heat and humidity increase the release of formaldehyde and the gas seri-ously harms the eyes.Paint, lacquer(抛光漆), etc.can also release dangerous gas into in-door air.
Construction materials can cause serious damage, especially when they contain asbes-tos(石棉).Asbestos is naturally present in rock formations worldwide.It consists of mi-neral substances composed of solid, non-combustible (不易燃的 ) fibers.These properties make asbestos a highly sought-after(受欢迎的) construction material.As early as 1931,however, public health officers in the United Kingdom revealed the connection between breathing in asbestos dust and such diseases as lung cancer.
The land on which a building is sited may also contribute to pollution.Some kinds of granite(花岗岩)or similar rocks contain traces of radium.As it breaks down, this natural-ly radioactive element produce some kind of radioactive gas that goes through tiny cracks in walls, floors and building materials, and makes its way into the building and the rooms.The better the homes are insulated, the more is the dangerous gas in indoor air.The main effect of this dangerous gas on health is to increase the risk of lung cancer.What is the main idea of the passage? A．Some building materials pollute indoor ai
B．Some factors cause indoor air pollutio
C．Asbestos can cause lung cance
D．The land on which houses are built contributes to indoor pollutio
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