Air Pollutants – Nitrogen Dioxide

Nitrogen dioxide is a gas. The molecules of the gas are made up of one nitrogen atom and 2 oxygen atoms.

The UK Government measures air pollution at many locations across the country. Almost 30% of these sites measured high annual levels of nitrogen dioxide in 2005 and many towns and cities have areas where Government targets for nitrogen dioxide are being exceeded. Electricity generation and road traffic are the two main sources of nitrogen dioxide. In most urban areas road traffic is by far the major source.

Nitrogen dioxide can irritate the lungs and lower resistance to respiratory infections such as flu. Nitrogen dioxide concentrations are high where vehicle emissions are high. So high levels of nitrogen dioxide are generally a reasonable indicator of exposure to other pollutants from vehicle exhausts.

In the environment, excessive levels of nitrogen dioxide can cause death in plants, and damage the leaves of many agricultural crops. Nitrogen dioxide is the damaging component of photochemical smog. High levels increase the acidity of rain (lower the pH), and thus lower the pH of water and soil. This lowered pH can have a variety of harmful effects, possibly even death, on a range of biological systems.

Nitrogen dioxide can be converted to nitrates, which can form a secondary pollutant of fine particles. Nitrogen dioxide can also contribute to ground level ozone via a complex series of chemical reactions in sunlight that also involve volatile organic compounds (VOCs).

How is nitrogen dioxide measured?

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