1. Department of Public Health and Clinical Medicine, Division of Medicine/Respiratory Medicine, Umeå University, Umeå, Sweden.
2. Department of Design Sciences, Division of Ergonomics and Aerosol Technology (EAT), Lund University, Lund, Sweden.
3. Department of Applied Physics and Electronics, Thermochemical Energy Conversion Laboratory, Umeå University, Umeå, Sweden.
4. Department of Physics, Division of Nuclear Physics, Lund University, Lund, Sweden.