求一篇地下工程的英语作文，150词

Health Risks of Underground Construction Work

Underground construction work includes tunnelling for roads, highways and railroads and laying pipelines for sewers, hot water, steam, electrical conduits, telephone lines. Hazards in this work include hard physical labour, crystalline silica dust, cement dust, noise, vibration, diesel engine exhaust, chemical vapours, radon and oxygen-deficient atmospheres. Occasionally this work must be done in a pressurized environment. Underground workers are at risk for serious and often fatal injuries. Some hazards are the same as those of construction on the surface, but they are amplified by working in a confined environment. Other hazards are unique to underground work. These include being struck by specialized machinery or being electrocuted, being buried by roof falls or cave-ins and being asphyxiated or injured by fires or explosions. Tunnelling operations may encounter unexpected impoundments of water, resulting in floods and drowning.