Nitrogen dioxide

Nitrogen dioxide in the city air is due to exhaust gases from traffic. The abbreviation NO2 refers to nitrogen dioxide.

The concentrations are high if the hourly value exceeds 150 µg/m3. The limit for the hourly value is 200 µg/m3 and the threshold value is 400 µg/m3. These values are very rarely exceeded in the Helsinki Metropolitan Area and when they are exceeded, the situation will be dealt through a contingency plan. On the annual level, concentrations are high and the limit value of 40 µg/m3 is exceeded in the city centre of Helsinki and along the heavily trafficked routes.