[1] Norwegian Inst Publ Hlth, Dept Air qual & Noise, Div Climate & Environm Hlth, POB 222 Skoyen, N-0213 Oslo, Norway
[2] Norwegian Inst Publ Hlth, Dept Chem Toxicol, Div Climate & Environm Hlth, POB 222 Skoyen, N-0213 Oslo, Norway
[3] Univ Oslo, Fac Math & Nat Sci, Dept Biosci, POB 1066, N-0316 Oslo, Norway
[4] Norwegian Inst Publ Hlth, Div Climate & Environm Hlth, POB 222 Skoyen, N-0213 Oslo, Norway