Air Pollution (health problems)

What is this air pollution being talked about?
It is the contamination of air by discharge of harmful substances.
Rapid industrialization and modernization have led to the worsening air pollution problem over the years. Industries, vehicles, continuous increase in the population and urbanization are some of the major factors responsible for air pollution. The following industries are among those that emit a great deal of pollutants into the air: thermal power plants, cement, steel, refineries, petrochemicals and mines. Air pollution results from a variety of causes, not all of which are within human control. The source of pollution maybe in one country but the impact of pollution maybe felt elsewhere.
Air pollution can cause health problems and above certain concentrations and durations, certain air pollutants are extremely dangerous and can cause severe injury or death. It can also damage the environment and property.