The high concentration of nitrogen dioxide (NO₂) in the ambient air is a direct threat to human health and human life. Nitrogen dioxide is a toxic, reddish-brown gas with a heavy acrid odor at higher concentrations and at lower concentrations it is colorless and odorless. Nitrogen dioxide poisoning depends on the duration, frequency and intensity of exposure.
Nitrogen dioxide is a mucosal irritant that, when associated with another air pollutant, causes lung disease such as OPD (obstructive pulmonary disease), asthma, chronic obstructive pulmonary disease, exacerbation of COPD, and in the worst case, death.
Its moderate solubility in water makes it easy to pass through the mucous membranes and enter the airways. Like most toxic gases, the inhalation dose determines the degree of respiratory toxicity. Prolonged exposure to low gas concentrations can have a deadly effect, as well as short exposure to high concentrations, such as chlorine poisoning. It is one of the biggest air pollutants that can cause various health problems, such as coronary heart disease or stroke.