WCAS/monitoring/SO2

Sulphur Dioxide

Characteristics

Sulphur dioxide (SO2) is formed during the processing and combustion of fossil fuels containing sulphur. It is a colourless gas with a pungent odour, and can be detected by taste and odour at concentrations as low as 300 ppb. Sulphur dioxide reacts in the atmosphere to form sulphuric acid and acidic aerosols, which contribute to acid rain. Sulphur dioxide combines with other atmospheric gases to produce fine particles, which may reduce visibility.

Brief exposure to high concentrations of sulphur dioxide and its products can produce human health effects, irritating the upper respiratory tract and aggravating existing cardiac and respiratory disease. Long-term exposure may increase the risk of developing chronic respiratory disease.

Sensitive vegetation may be injured by exposure to high sulphur dioxide concentrations. Symptoms include a chlorotic appearance of the leaf with silvering or bronzing of the underside.

Sources

The primary emitting sources are, base metal smelters, fossil–fueled electric power plants , upstream oil and gas industry (e.g. natural gas plants, oil sands) , other industrial sources (e.g. cement plants, petroleum refineries, pulp and paper mills) as well as transportation sources (e.g. ships, off-road diesel vehicles).

Alberta Guidelines

Alberta Environment and Parks has adopted the Environment Canada's most rigorous objectives for sulphur dioxide. The Alberta guidelines for ambient air are:

  • 1–hour average of 170 ppb
  • 24–hour average of 60 ppb
  • an annual average of 10 ppb
Concentration (ppb) Exposure Time Human Symptoms and Other Effects
400,000 Lung edema; bronchial inflammation
20,000 Eye irritaiton; coughing in health adults
15,000 1 hour Decreased mucoduar-y activity
10,000 10 min Bronchospasm
10,000 2 hours Visible foliar injury to vegetation in arid regions
8,000 Throat irritation in healthy adults
5,000 10 min Increased airway resistance in healthy adults at rest
1,000 10 min Increased airway resistance in asthmatics at rest and in healthy adults at exercise
1,000 5 min Visible injury to sensitive vegetation in humid regions
500 10 min Increased airway resistance in asthmatics at exercise
500 Odour threashold
500 1 hour Visibile injury to sensitive vegetation in humid regions
500 3 hours US national secondary ambient air quality standard
200 3 hours Visible injury to sensitive vegetation in humid regions
190 24 hours Aggravation of chronic respiratory disease in adults
170 1 hour Alberta ambient air quality guideline
140 24 hours US national primary ambient air quality standard
70 annual Aggravation of chronic respiratory disease in children
60 24 hours Alberta ambient air quality guideline
30 annual US national primary ambient air quality standard
10 annual Alberta ambient air quality guideline

Air Quality Data

Date Range – From
Date Range – To
Station

Sulphur Dioxide (SO2) Trends

Time Range

Stations