title: The influence of seasonal climate variability on mortality in pre-industrial Sweden.
abstract: BACKGROUND
  Recent studies have shown an association between weather and climatic factors with mortality, cardiovascular and infectious diseases. We used historical data to investigate the impact of seasonal temperature and precipitation on total mortality in Uppsala, Sweden, during the first two stages of the demographic transition, 1749-1859.
  
  
  METHODS
  We retrieved mortality and population numbers of the Uppsala Domkyrka parish from digitised parish records and obtained monthly temperature and precipitation measures recorded in Uppsala during that time. Statistical models were established for year-to-year variability in deaths by annual and seasonal temperature and precipitation, adjusting for longer time trends. In a second step, a model was established for three different periods to study changes in the association of climate variability and mortality over time. Relative risks (RR) with 95% confidence intervals (CI) were calculated.
  
  
  RESULTS
  Precipitation during spring and autumn was significantly associated with annual mortality (spring RR 0.982, CI 0.965-1.000; autumn RR 1.018, CI 1.004-1.032, respectively, per centimetre increase of precipitation). Higher springtime temperature decreased annual mortality, while higher summer temperature increased the death toll; however, both were only borderline significant (p=0.07). The significant effect of springtime precipitation for mortality was present only in the first two periods (1749-1785 and 1786-1824). On the contrary, the overall effect of autumn precipitation was mainly due to its relevance during the last period, 1825-1859 (RR 1.024, CI 0.997-1.052). At that time, higher winter precipitation was found to decrease mortality.
  
  
  CONCLUSIONS
  In urban Uppsala, during the 18th and 19th century, precipitation appeared to be a stronger predictor for mortality than temperature. Higher spring precipitation decreased and higher autumn precipitation increased the number of deaths. However, this association differed before and during the early stages of industrialisation. Further research shall take age-specific differences into account, as well as changes in socio-economic conditions during that time.
authors.affiliation: Department of Public Health and Clinical Medicine, Umeå Centre for Global Health Research, Umeå University, Umeå, Sweden. barbara.schumann@epiph.umu.se
authors.forename: Barbara
authors.initials: B
authors.lastname: Schumann
authors.forename: Sören
authors.initials: S
authors.lastname: Edvinsson
authors.forename: Birgitta
authors.initials: B
authors.lastname: Evengård
authors.forename: Joacim
authors.initials: J
authors.lastname: Rocklöv
mesh_terms: D002980:Climate; D049671:History, 18th Century; D049672:History, 19th Century; D006801:Humans; D009026:Mortality / Q000266:history* / Q000639:trends; D012621:Seasons; D012959:Socioeconomic Factors; D013548:Sweden / Q000453:epidemiology; D014887:Weather
keywords: Sweden; climate variability; mortality; pre-industrial period; urban population
references.citation: Int Arch Occup Environ Health. 2011 Apr;84(4):361-9
references.pmid: 20957489
references.citation: Int Arch Occup Environ Health. 2007 Jul;80(7):615-26
references.pmid: 17468879
references.citation: Proc Natl Acad Sci U S A. 2012 Mar 27;109(13):4730-7
references.pmid: 22315419
references.citation: Soc Hist Med. 1992 Apr;5(1):71-94
references.pmid: 11612777
references.citation: Int J Circumpolar Health. 2005 Dec;64(5):523-33
references.pmid: 16440614
references.citation: BMC Public Health. 2011 May 10;11:289
references.pmid: 21569269
references.citation: Science. 2004 Mar 5;303(5663):1499-503
references.pmid: 15001774
references.citation: Zoonoses Public Health. 2009 Apr;56(3):150-6
references.pmid: 18771520
references.citation: Popul Stud (Camb). 2005 Nov;59(3):321-37
references.pmid: 16249153
references.citation: Glob Health Action. 2009 Nov 11;2:
references.pmid: 20231906
references.citation: Environ Res. 2012 Jan;112:218-24
references.pmid: 22226140
references.citation: Milbank Mem Fund Q. 1971 Oct;49(4):509-38
references.pmid: 5155251
references.citation: Int J Environ Res Public Health. 2010 Jun;7(6):2607-19
references.pmid: 20644691