1. Design Engineer, Ramboll Finland Oy, Niemenkatu 73, 15140 Lahti, Finland (corresponding author).
2. Professor, Water Resources and Environmental Engineering Laboratory, Dept. of Process and Environmental Engineering, Faculty of Technology, Univ. of Oulu, P.O. Box 4300, 90014 Oulu, Finland.
3. Finnish Institute of Occupational Health, Topeliuksenkatu 41 a A, 00250 Helsinki, Finland.