Excessive NOx emissions can lead to which environmental issue?

Excessive NOx, or nitrogen oxides, emissions primarily contribute to air pollution and can significantly impact human health, particularly respiratory systems. NOx compounds can react in the atmosphere to form ground-level ozone, a key component of smog, which presents serious health risks as it can irritate the airways, leading to conditions like asthma and bronchitis. Additionally, these emissions can contribute to the formation of fine particulate matter, which can penetrate deep into the lungs and further exacerbate respiratory problems.

While other issues like global warming, water contamination, and noise pollution are critical environmental concerns, they are not directly associated with the emissions of NOx. Nitrogen oxides are particularly noted for their adverse effects on air quality and human health, solidifying their role in causing air pollution and respiratory problems.