Mercury is a liquid silver-white metal, at room temperature that can be volatile, mercury vapor is very toxic, mercury thermometer accidentally broken and dropped on the ground will be scattered into beads, not timely collection, cleaning will soon evaporate into the air, through the respiratory tract caused by poisoning symptoms. If you accidentally touch the skin can also enter the body, which will damage the health of the body, mercury can damage the brain, and can even damage the reproductive system causing deformities. The maximum permissible concentration of metallic mercury in the air is 0.01mg/m^3, and people can be poisoned quickly in an environment where the mercury concentration is 1.2-8.5mg/m^3. A mercury thermometer contains 1g of mercury, broken and fallen on the ground in 1 room 15m^2, mercury if completely volatile air mercury concentration can reach 22mg/m^3, this value greatly exceeds the allowable standard, seriously endangering human health.