Sulphur dioxide

Sulphur dioxide in outdoor air is formed through energy generation and ships’ emissions. Concentrations in the Helsinki Metropolitan Area are nowadays low, and won’t exceed the limit values. The abbreviation SO2 refers to sulphur dioxide.

Air quality is poor when the hourly value exceeds 250 µg/m3. Sulphur dioxide’s limit value for an hour is 350 µg/m3 and the limit for 24 hours is 125 µg/m3. The public must be warned about health hazards if the warning threshold (500 µg/m3) continues to be exceeded for three hours. Concentrations this high are very unlikely in the Helsinki Metropolitan Area.