Abstract: Cities have multiplied and expanded rapidly worldwide over the past two centuries. Urban living is the keystone of modern human ecology. Cities are sources of creativity and technology, and they are the engines for economic growth. However, they are also sources of health hazards from the environment. As the number of urban consumers and their material expectations rise and as the use of fossil fuels increases. Urban populations have long been incubators and gateways for modern diseases. Shch as allergic diseases, tuberculosis , nervous system diseases ,Minamata disease and Itai-itai disease caused by methyl mercury and cadmium, some diseases increased cardiovascular morbidity and mortality in general.Various environmental factors that may enhance sensitization include NO2, SO2, ozone, and diesel particles. Atmospheric air pollution is the environmental factor mostly considered as responsible for the asthma increase. These fine particles tend to be generated from human activities, particularly the combustion of fossil fuels, especially diesel fuel. The health effects of lead exposure include developmental neurotoxicity, reproductive dysfunction and toxicity to the kidneys, blood and endocrine systems.It is concluded that urban environmental factors from the physical, chemical, biological, and psychological environment do influence the development of modern diseases.We must develop policies to solve the urban environmental health hazards and environmental problems.