title: The association between green space and cause-specific mortality in urban New Zealand: an ecological analysis of green space utility.
abstract: BACKGROUND
  There is mounting international evidence that exposure to green environments is associated with health benefits, including lower mortality rates. Consequently, it has been suggested that the uneven distribution of such environments may contribute to health inequalities. Possible causative mechanisms behind the green space and health relationship include the provision of physical activity opportunities, facilitation of social contact and the restorative effects of nature. In the New Zealand context we investigated whether there was a socioeconomic gradient in green space exposure and whether green space exposure was associated with cause-specific mortality (cardiovascular disease and lung cancer). We subsequently asked what is the mechanism(s) by which green space availability may influence mortality outcomes, by contrasting health associations for different types of green space.
  
  
  METHODS
  This was an observational study on a population of 1,546,405 living in 1009 small urban areas in New Zealand. A neighbourhood-level classification was developed to distinguish between usable (i.e., visitable) and non-usable green space (i.e., visible but not visitable) in the urban areas. Negative binomial regression models were fitted to examine the association between quartiles of area-level green space availability and risk of mortality from cardiovascular disease (n = 9,484; 1996 - 2005) and from lung cancer (n = 2,603; 1996 - 2005), after control for age, sex, socio-economic deprivation, smoking, air pollution and population density.
  
  
  RESULTS
  Deprived neighbourhoods were relatively disadvantaged in total green space availability (11% less total green space for a one standard deviation increase in NZDep2001 deprivation score, p < 0.001), but had marginally more usable green space (2% more for a one standard deviation increase in deprivation score, p = 0.002). No significant associations between usable or total green space and mortality were observed after adjustment for confounders.
  
  
  CONCLUSIONS
  Contrary to expectations we found no evidence that green space influenced cardiovascular disease mortality in New Zealand, suggesting that green space and health relationships may vary according to national, societal or environmental context. Hence we were unable to infer the mechanism in the relationship. Our inability to adjust for individual-level factors with a significant influence on cardiovascular disease and lung cancer mortality risk (e.g., diet and alcohol consumption) will have limited the ability of the analyses to detect green space effects, if present. Additionally, green space variation may have lesser relevance for health in New Zealand because green space is generally more abundant and there is less social and spatial variation in its availability than found in other contexts.
authors.affiliation: School of GeoSciences, The University of Edinburgh, Edinburgh, UK.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Richardson
authors.forename: Jamie
authors.initials: J
authors.lastname: Pearce
authors.forename: Richard
authors.initials: R
authors.lastname: Mitchell
authors.forename: Peter
authors.initials: P
authors.lastname: Day
authors.forename: Simon
authors.initials: S
authors.lastname: Kingham
mesh_terms: D002318:Cardiovascular Diseases / Q000401:mortality*; D002423:Cause of Death / Q000639:trends; D017753:Ecosystem; D004779:Environment Design; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000401:mortality*; D008297:Male; D009520:New Zealand; D012111:Residence Characteristics / Q000145:classification; D012307:Risk Factors; D012959:Socioeconomic Factors; D014504:Urban Health
references.citation: BMJ. 2005 Sep 17;331(7517):611-2
references.pmid: 16113034
references.citation: Ann Behav Med. 2003 Spring;25(2):100-4
references.pmid: 12704011
references.citation: Eur J Cardiovasc Prev Rehabil. 2008 Jun;15(3):239-46
references.pmid: 18525377
references.citation: J Epidemiol Community Health. 2009 Dec;63(12):967-73
references.pmid: 19833605
references.citation: J Epidemiol Community Health. 2007 Aug;61(8):681-3
references.pmid: 17630365
references.citation: Int J Environ Health Res. 2005 Oct;15(5):319-37
references.pmid: 16416750
references.citation: Am J Prev Med. 2002 Apr;22(3):188-99
references.pmid: 11897464
references.citation: Health Place. 2009 Jun;15(2):586-595
references.pmid: 19022699
references.citation: Lancet. 2008 Nov 8;372(9650):1655-60
references.pmid: 18994663
references.citation: J Expo Sci Environ Epidemiol. 2008 Mar;18(2):200-10
references.pmid: 17668011
references.citation: Am J Prev Med. 2005 Feb;28(2 Suppl 2):159-68
references.pmid: 15694524
references.citation: BMC Public Health. 2008 Jun 10;8:206
references.pmid: 18544169
references.citation: Int J Epidemiol. 2007 Apr;36(2):348-55
references.pmid: 17182634
references.citation: Annu Rev Psychol. 1997;48:411-47
references.pmid: 9046565
references.citation: Health Place. 2009 Jun;15(2):482-490
references.pmid: 19038571
references.citation: Health Place. 2000 Jun;6(2):67-79
references.pmid: 10785349
references.citation: Prev Med. 2008 Sep;47(3):299-303
references.pmid: 18533242
references.citation: Cancer Epidemiol Biomarkers Prev. 2001 Apr;10(4):287-301
references.pmid: 11319168
references.citation: Science. 1984 Apr 27;224(4647):420-1
references.pmid: 6143402
references.citation: J Epidemiol Community Health. 2006 Jul;60(7):587-92
references.pmid: 16790830
references.citation: J Epidemiol Community Health. 2002 Dec;56(12):913-8
references.pmid: 12461111
references.citation: BMJ. 2000 Apr 29;320(7243):1200-4
references.pmid: 10784551
references.citation: J Epidemiol Community Health. 2008 May;62(5):e9
references.pmid: 18431834