Nitrogen oxides NOx , which primarily consist of nitrogen dioxide NO2 and nitric oxide NO , play a significant role in the formation of smog. Smog is a type of air pollution that results from the interaction of various pollutants, including nitrogen oxides, volatile organic compounds VOCs , and sunlight.The process of smog formation begins when nitrogen oxides are released into the atmosphere, primarily from the burning of fossil fuels in vehicles, power plants, and industrial processes. Once in the atmosphere, nitrogen oxides react with VOCs in the presence of sunlight to form ozone O3 . This reaction is facilitated by the presence of sunlight, which provides the energy necessary for the chemical reactions to occur.Ozone, along with other particulate matter and pollutants, contributes to the formation of smog. Smog is typically characterized by a hazy, brownish-yellow appearance and reduced visibility. It is most commonly observed in urban areas with high levels of vehicle emissions and industrial activity.Smog can have significant impacts on human respiratory health. The primary component of smog, ozone, is a powerful oxidant that can cause irritation and inflammation in the respiratory system. Exposure to elevated levels of ozone can lead to symptoms such as coughing, wheezing, shortness of breath, and chest pain. It can also exacerbate pre-existing respiratory conditions, such as asthma and chronic obstructive pulmonary disease COPD .In addition to ozone, smog contains particulate matter, which can also have detrimental effects on respiratory health. Particulate matter can be inhaled deep into the lungs, causing irritation and inflammation. Long-term exposure to high levels of particulate matter has been associated with an increased risk of developing respiratory and cardiovascular diseases.To mitigate the impacts of smog on human health, it is essential to reduce the emissions of nitrogen oxides and other pollutants that contribute to its formation. This can be achieved through the implementation of cleaner technologies, stricter emission standards, and promoting alternative modes of transportation, such as public transit, cycling, and walking.