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Smog alert

Smog alert system includes NO2, SO2 and O3.

Threshold values for alert

The population is informed if the concentration on an hourly basis exceeds the following values

  • Concentrations of NO2 exceeds 400 µ g/m3 or the concentration of SO2 exceeds 500 µ g/m3. In both cases, the overrun stretch over 3 consecutive hours over a wider area (e.g. over an entire city or region (zone)).
  • O3 exceeds 180 µ g/m3

Emitted a smog alert if the concentration of O3 on an hourly basis in 3 consecutive hours exceeds 240 µ g/m3.

In practice, only tærskelværien for information for ozone will be exceeded in Denmark. It happens very rarely (with years).

See also limit values.