Complex sentence: A stationary source in air quality parlance is any fixed emitter of air pollutants, such as fossil fuel burning power plants, petroleum refineries, petrochemical plants, food processing plants and other heavy industrial sources.
Split into simpler sentences: A stationary source in air quality parlance is any fixed emitter of air pollutants, such as a factory. Significant types of stationary sources are fossil fuel burning power plants, petroleum refineries, chemical plants, food processors and other heavy industrial sources.