Air Quality is a general measurement of the quality of the environment. The measurement naturally includes air quality, but also measures noise pollution, litter, water quality, and many other kinds of pollution.
Air Quality is primarily only a concern for a nation's Environmentalists. However, poor Air Quality raises the cost of healthcare and is the main contributor in negative situations such as rampant Pollution and Asthma Epidemics.
Air Quality is harmed by industrialization; high GDPs and excessive travel by car or airplane will all cause pollution. A government can enact various policies to reduce the impact industrialized society has on the environment, but most such policies lower the GDP and upset the Capitalists and the Motorists.