Smog is a type of air pollution that combines smoke and fog, often seen in urban areas. It is created when pollutants from vehicles, factories, and other sources mix with moisture in the air. This mixture can reduce visibility and harm human health, leading to respiratory issues and other problems. There are two main types of smog: industrial smog and photochemical smog. Industrial smog is typically found in areas with heavy manufacturing, while photochemical smog occurs when sunlight reacts with pollutants like nitrogen oxides and volatile organic compounds. Both types can have serious environmental and health impacts.