Air pollution is the introduction of particulates, biological molecules, or other harmful materials into Earth's atmosphere, causing disease, death to humans, damage to other living organisms such as food crops, or the natural or built environment.
We cannot often see pollution in the air caused by industries and cars emissions, so testing (monitoring) must be done to check the air quality. Monitoring the air quality is essential for local authorities as well as for major public and private industries to understand and prevent air pollution and assess emission sources