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在大城市里,过敏病越来越普遍。特别是有1/10的儿童得这种病,引起人们的关切。最常见的过敏有气喘、干草热、皮肤斑疹等。大气污染、花粉、饮食质量不高、霉孢子、螨虫和室尘,这些都是引起过敏的刺激物。室内的灰尘主要来自土壤,其次来自海洋——空气中脯有几百万吨比的晶体。此外,火山也排放到空气中很多颗粒。撒哈拉大沙漠一年也有60000000——2000000000吨浅粉红色的尘土排放到空气中。地球外的尘土来自慧星和陨星。这些尘土增加地球的重量达10
In big cities, allergies are becoming more common. In particular, 1 in 10 children have this disease and cause for concern. The most common allergies have asthma, hay fever, skin rashes and so on. Air pollution, pollen, poor diet, mold spores, mites and dust are all irritants that cause allergies. Dust in the interior comes mainly from the soil, followed by the oceans, which have millions of tons of crystals in the air. In addition, volcanoes also discharge many particles into the air. A year there are 60000000 - 2000000000 tons of light pink dust in the Sahara desert into the air. Earth’s dust comes from comets and meteorites. These dusts increase the weight of the earth to 10