Primary Pollutants: Primary pollutants are directly emitted into the environment from human activities or natural sources. Unlike secondary pollutants, they do not require any chemical reactions to form.
Ozone (O3): Ozone is a secondary pollutant formed by complex chemical reactions involving sunlight, nitrogen oxides (NOx), volatile organic compounds (VOCs), and other pollutants. It is a major component of smog.
Acid Rain: Acid rain is a secondary pollutant formed when primary pollutants, such as sulfur dioxide (SO2) and nitrogen oxides (NOx), react with water vapor in the atmosphere. It can have harmful effects on ecosystems, buildings, and human health.