Exposure to high levels of nitrogen oxides NOx in air pollution can have significant negative effects on human respiratory function and increase the risk of respiratory diseases. Nitrogen oxides are a group of gases that include nitric oxide NO and nitrogen dioxide NO2 . They are primarily produced from combustion processes, such as those occurring in motor vehicles, power plants, and industrial facilities.When humans are exposed to high levels of nitrogen oxides, several mechanisms can contribute to respiratory problems and diseases:1. Direct irritation and inflammation: Nitrogen oxides can irritate the respiratory tract, causing inflammation and damage to the cells lining the airways. This can lead to symptoms such as coughing, wheezing, and shortness of breath. Prolonged exposure can cause chronic inflammation, which may contribute to the development of chronic respiratory diseases like asthma and chronic obstructive pulmonary disease COPD .2. Increased susceptibility to infections: The inflammation and damage caused by nitrogen oxides can impair the respiratory tract's natural defenses against infections. This can make individuals more susceptible to respiratory infections, such as pneumonia and bronchitis.3. Oxidative stress: Nitrogen oxides can generate reactive oxygen species ROS in the respiratory tract, leading to oxidative stress. This can cause further damage to the cells lining the airways and contribute to the development of respiratory diseases.4. Altered immune response: Exposure to nitrogen oxides can also affect the immune system, leading to an altered immune response. This can result in an increased risk of allergic reactions and asthma exacerbations.5. Interaction with other pollutants: Nitrogen oxides can interact with other air pollutants, such as volatile organic compounds VOCs , to form secondary pollutants like ozone and particulate matter. These secondary pollutants can also have negative effects on respiratory health.Overall, exposure to high levels of nitrogen oxides in air pollution can lead to both acute and chronic respiratory problems. It can cause irritation and inflammation in the respiratory tract, impair the body's natural defenses against infections, and contribute to oxidative stress and altered immune responses. These factors can increase the risk of developing respiratory diseases, such as asthma, COPD, and respiratory infections. Reducing exposure to nitrogen oxides and other air pollutants is essential for protecting respiratory health and preventing respiratory diseases.