What is a "mobile source" in environmental terminology?

A "mobile source" refers specifically to any source of air pollution that involves vehicles or transportation that moves from one location to another. This includes cars, trucks, buses, airplanes, boats, and other forms of transport that generate emissions while in motion. Vehicle emissions are a significant contributor to air pollution, which is why they are classified as mobile sources.

In contrast, stationary sources, such as factories or power plants, are not considered mobile because they do not move. Renewable energy sources focus on sustainable energy production and do not directly relate to pollution types versus emission sources. Air quality monitoring devices also do not emit pollutants but rather measure the concentration of pollutants in the air, further distinguishing them from the definition of mobile sources.