human
What is air pollution, and what are the causes of it?
assistant
Air pollution is the presence of harmful substances in the atmosphere. These can be gases or particles that come from a variety of sources including vehicles, factories, power plants, burning of fossil fuels, etc. The most common pollutants are carbon dioxide (CO2), nitrogen oxides (NOx), sulfur dioxide (SO2), and volatile organic compounds (VOCs). These pollutants react with sunlight and form ground-level ozone (O3) which is a major component of smog. Ozone is a colorless gas formed when oxygen molecules interact with other molecules such as VOCs, NOx, and SO2. This reaction creates a photochemical smog that can cause respiratory problems, reduced visibility, and damage to vegetation.