At high concentrations, nitrogen dioxide can cause disturbances in the central nervous system, circulatory system, and enzyme system. Because it does not dissolve easily in water and remains in a gas form, it can penetrate to the most remote portions of the respiratory tract. At high concentrations it can be fatal. At lower concentrations it can irritate the lungs and lower the body's resistance to respiratory infections such as influenza, pneumonia, and bronchitis. As mentioned above, nitrogen oxides that combine with hydrocarbons and other volatile organic compounds form ozone.
Ozone can pose serious health problems.
It can inflame and irritate breathing passages, reduce resistance to illnesses, and cause coughing and wheezing. In addition to their effects on human health, nitrogen oxides can damage other organisms and materials through their role in producing ozone. Ozone can reduce the size of plants and cause leaf spotting. It can change the color of clothing dyes, cause fabrics to lose strength, and corrode some metals. Nitrogen oxides also produce a brown haze that impairs visibility.