Nitrogen oxides (NOx) are a group of gases composed of nitrogen and oxygen, primarily including nitric oxide (NO) and nitrogen dioxide (NO2). They are produced during combustion processes, such as in vehicles, power plants, and industrial facilities. NOx plays a significant role in air pollution and can contribute to the formation of ground-level ozone and smog. These gases can have harmful effects on human health and the environment. Exposure to nitrogen oxides can lead to respiratory issues and aggravate conditions like asthma. Additionally, NOx emissions can contribute to acid rain, which can damage ecosystems, buildings, and water sources.