What is the primary constituent of smog?

The primary constituent of smog is ozone. Smog, particularly in urban areas, is a type of air pollution that occurs when sunlight reacts with pollutants like nitrogen oxides and volatile organic compounds. This chemical reaction leads to the formation of ground-level ozone, which is a significant component of smog. Ozone at ground level is harmful to human health, causing respiratory issues and other health problems, while also contributing to environmental damage.

Carbon dioxide is primarily associated with climate change rather than smog formation. Nitrogen oxides do contribute to smog by reacting in the atmosphere to form ozone but are not themselves the main constituent. Particulate matter consists of tiny particles in the air that can be part of smog but are different from the ozone that characterizes photochemical smog. Therefore, ozone stands out as the primary constituent responsible for the smog phenomenon.