An industrial city or industrial town is a town or city in which the municipal economy, at least historically, is centered around industry, with important factories or other production facilities in the town. It has been part of most countries' industrialization process. Air pollution and toxic waste have contributed to the lower life expectancy in some industrial cities. Industrial cities are distinguished from port cities or other transportation hubs, which deal in services. In countries with strong central planning, such as China and India, a city could be created on paper, and then industry found to locate there.