Explanation – Nitrogen dioxide is a pollutant released from vehicle exhaust that contributes to the formation of ground-level ozone and smog. When nitrogen dioxide and other pollutants, such as volatile organic compounds (VOCs), react in the presence of sunlight, they form ground-level ozone, a major component of smog. Carbon dioxide (CO2), methane (CH4) and Sulfur dioxide (SO2) are also emitted from vehicle exhaust, but they do not directly contribute to the formation of ground-level ozone and smog.

Source: Forum IAS