Does living in big cities do harm to people's health? A prevailing trend of living in big cities brings people convenience but also some drawbacks. Metropolitan cities seem to have low air quality on the whole. Huge exhaust fume emission and haze are harmful to residents' health, especially lungs.The number of patients suffering from lung cancer or related diseases is constantly increasing. Besides, most people living in big cities keep a rapid pace of life under huge stress and pressure, which can contribute to a sudden death if lasting a long time. For example, working overtime too much and staying awake at night too often could break down our normal body functions, thereby accumulating petty diseases to big ones. In addition, because of a lack of meal time, people may choose to eat fast food or take out. These are short of nutrition and many of them are unhygenic, not good to health. However, we can not ignore the complete and high quality medical service big cities take to us. Many migrants migrate from countryside to urban areas in search of higher medical level in case of an severe illness. Although big cities provide better medical systems, living there has a harmful impact on people's health.