Nitrogen oxides (NOX)

Oxides of nitrogen, mostly in the form of nitrogen oxide (NO) and nitrogen dioxide (NO2), are produced by the high temperature combustion of fossil fuels. Nitrogen oxide is the predominant species emitted by combustion sources but it is rapidly changed to nitrogen dioxide in the atmosphere.

Nitrogen dioxide is a reddish-brown gas with a pungent irritating odour. It has been linked to respiratory disease and contributes to acid rain. It plays a major role in atmospheric photochemical reactions and ground level ozone formation and destruction.

Exposure of vegetation to high concentrations of nitrogen oxides results in silvering of the lower leaf surface. A waxy appearance appears shortly after exposure followed by bronzing after two or three days.

Motor vehicles account for over 50% of the total NO2 genetared, however, any combustion source will emit nitrogen dioxide (e.g. power plants, furnaces, space heaters, etc.) Some natural sources include volcanoes, lightning, biological decay, oceans.

What Can We Do?

  • Conserve Energy. By reducing your demand on the power generating stations you will help reduce the amount of NO2 emitted. Also, consider finding alternative forms of transportation (eg: walking, biking, public transit, car pooling) or plan your outings in order to minimize your overall travel distance. Do not allow your vehicle to idle for long periods (eg: car starters).

  • Support alternative fuels. Utilizing ‘Greenpower’, like wind, and solar power will reduce the amount of NO2 being generated.

  • Properly insulate your house and body.

Alberta Guidelines

Alberta Environments guideline are based on the prevention of human health effects. They are equal to the most rigorous of Environment Canada's ambient air quality objectives. The Alberta Guidelines for nitrogen dioxide, the major component of nitrogen oxides in the ambient atmosphere are:

  • 1-hour average of 210 ppb;
  • 24-hour average of 110 ppb;
  • an annual average of 30 ppb

Table of Human Symptoms and Other Effects

Concentration (ppb) Exposure Time Human Symptoms and Other Effects
300,000 Rapid death
150,000 Death after 2 or 3 weeks by bronchiolitis fibrosa obliterans
50,000 Reversible, nonfatal bronchiolitis
10,000 Impairment of ability to detect odour of NO2
5,000 15 min Impairment of normal transport of gases between the blood and lungs in health adults
2,500 2 hours Increased airway resistance in healthy adults
2,000 4 hours Foliar injury to vegetation
1,000 15 min Increased airway resistance in adults with bronchitis
1,000 48 hours Slight leaf spotting of pinto bean, endive, and cotton
300 Brownish color of target — 1 km distant
250 Decrease of growth and yeild of tomatoes and oranges
212 1 hour Alberta ambient air quality guideline
200 8 hours Yellowing of white fabrics
120 Odour perception threshold
106 24 hours Alberta ambient air quality guideline
100 12 weeks Fading of dyes on cotton and rayon
100 20 weeks Reduction of growth of Kentucky bluegrass
32 annual Alberta ambient air quality guideline
30 Brownish color of target — 10 km distant (note: target = receptor)
3 Brownish color of target — 100 km distant

Get Involved

As an airshed, educating about air quality is an essential part of what we do. It is important to us as an organization to inform through not only sharing air quality data but also providing tips on how we can all do our part to reduce air pollution and serve as environmental stewards at an individual level.

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