Are there the regional differences in the association between long-term exposure to PM2.5 and all-cause natural mortality in Denmark? The Danish Nurse Cohort study. (October 2019) - R, So; J, Jørgensen; M, Ketzel; S, Loft; B, Brunekreef; G, Hoek; T, Sigsgaard; C, Backalarz; Y, Lim; Z, Andersen