九九九在线_国产精品无码久久久久一区二区_秋霞午夜鲁丝一区二区老狼_久草91_久热99_精品福利一区二区三区_爱爱福利社_一级α片免费看刺激高潮视频_九九精品网_激烈娇喘叫1v1高h糙汉_av天天干_操操操av_日韩视频一区二区三区_欧美黑人xxx_欧美性猛交xxxx乱大交退制版

First, the harm of radonRadon is a kind of gas produced by the decay of radium. It is the only natural radioactive inert gas in nature. Its specific gravity is 7.5 times that of air. It hides in the corners of our lives, without color or smell.One of the great mysteries of the 20th century was that those who entered the pyramids would soon die of a sudden illness. People say the ancient Egyptians put a curse on the pyramids. The mystery of the pyramids didn't come to light until Canadian and Egyptian researchers discovered radon gas in the site.Volatile harmful gases can be reduced to safe levels over time. The danger of radon is that it is not volatile. Indoor radon does not decrease over time. Therefore, radon concentration in underground dwellings is much higher than that in above-ground dwellings.The main hazards of radon to human body are:1. Lead to lung cancer. It is the second leading cause of lung cancer, which kills 50,000 people in China each year due to radon and its progeny.2. Leukemia.3, the loss of fertility, fetal abnormalities, genetic abnormalities and so on.In addition, radon can also affect people's nervous system through human fat, making people depressed and drowsy. Radon gas has become a super invisible killer of home health.Second, the source of radonThere are four main sources of indoor radon:1. Radon precipitated from the soil. The soil and rocks containing uranium, radium and thorium in the deep strata often have high concentration of radon, which can enter the soil through the strata fracture zone and spread to the room along the cracks.2. Radon precipitated from building materials. Granite, brick and sand, especially natural stone materials containing radioactive elements, are easy to release radon.3, outdoor air into the indoor radon. The radiation dose of radon in outdoor air is very low, but once it enters the room, it will accumulate and is not easy to disappear. Constant ventilation can be improved.4. Radon released from natural gas in heating and kitchen equipment.Above, articles 1 and 2 are the main sources. Therefore, when new buildings are built, radon detection must be carried out.