Nitrogen oxides (NOx) are a group of gases that include nitrogen dioxide (NO2) and nitric oxide (NO). They are produced during combustion processes, such as those in vehicles, power plants, and industrial facilities. NOx gases play a significant role in air pollution and can contribute to the formation of smog and acid rain. These gases can have harmful effects on human health and the environment. Exposure to NOx can lead to respiratory issues and aggravate conditions like asthma. Additionally, NOx emissions are regulated by environmental agencies to help improve air quality and protect public health.