What is one anthropogenic source of nitrogen oxides (NOx)?

Vehicle emissions are a significant anthropogenic source of nitrogen oxides (NOx). When fossil fuels are burned in internal combustion engines, such as in cars and trucks, they produce NOx as a byproduct of combustion. This happens because at high temperatures, nitrogen in the air reacts with oxygen, resulting in the formation of NOx compounds. These emissions contribute to various environmental problems, including the formation of ground-level ozone and smog, which can have detrimental effects on human health and the environment.

While industrial processes and natural gas extraction can also release NOx, they are not as predominant as vehicle emissions in urban areas, where traffic is the primary source of air pollution. Volcanic eruptions generally do not fall under anthropogenic sources, as they are natural events. Therefore, vehicle emissions are a clear example of human activity contributing to the presence of nitrogen oxides in the atmosphere.