WCAS/monitoring/SO2
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.
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 Environment has adopted the Environment Canada's most rigorous objectives for sulphur dioxide. The Alberta guidelines for ambient air are:
| 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 |