A tracer investigation of traffic emissions from the Vålerenga tunnel at Etterstad.

Eighteen tracer experiments were conducted in and near the northbound tube of the Vålerenga tunnel. The tracer tests confirm previous modelling results concerning air pollution impact from the tunnel. The tracer gas concentration 60 to 150 m from the tunnel was below 10% of the concentration in the tunnel outlet. For wind along Strømsveien, tracer gas concentrations 40-60 meters from the road was 10% of the roadside concentration.