Why did levels of nitrogen increase in the atmosphere?

Levels of nitrogen in the atmosphere have remained relatively stable, primarily because nitrogen gas (N₂) makes up about 78% of the Earth's atmosphere and is not significantly altered by human activities. However, increases in nitrogen compounds, such as nitrogen oxides (NOx), are primarily due to industrial activities, combustion of fossil fuels, and agricultural practices, which release reactive nitrogen into the atmosphere. These compounds can contribute to air pollution and affect climate and ecosystem health. Overall, while atmospheric nitrogen levels remain constant, its reactive forms have increased due to human influence.