Criteria Pollutant: Nitrogen Oxides

Nitrogen gas comprises about 80 percent of the air. At high temperatures it can react with oxygen, forming different gaseous compounds. Collectively they are called nitrogen oxides. Nitrogen dioxide is one of the most important. These gases are formed when fossil fuels are burned in cars, power plants and factories. These gases are also an ingredient in making ground-level ozone. They are also a precursor to acid rain, which can affect terrestrial and aquatic ecosystems.

Health and Other Effects
Nitrogen oxides affect human health in ways similar to ozone. They include:

• A measurable decrease in lung function, especially in asthmatics
• Lung irritation
• Increased rates of lung disease
• Destroyed lung tissue, leading to emphysema

Nitrogen Oxides can also:

• Seriously injure vegetation at certain concentrations (bleaching or killing plant tissue, causing leaves to fall, reducing growth rate)
• Deteriorate fabric and fade dyes
• Corrode metals
• Reduce visibility

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