Which emission component has a direct relationship with smog formation?

The emission component that has a direct relationship with smog formation is nitrogen oxides. When emitted into the atmosphere, nitrogen oxides react with volatile organic compounds (VOCs) in the presence of sunlight, leading to the formation of ground-level ozone. This ozone is a key component of smog, which can adversely affect air quality and public health.

Nitrogen oxides are often produced from vehicle emissions and industrial processes, and their presence in the atmosphere is a significant factor in the chemical reactions that create smog. Managing and reducing nitrogen oxides, therefore, is crucial for controlling smog formation and improving air quality in urban areas.