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The association between green space and cause-specific mortality in urban New Zealand: an ecological analysis of green space utility.

Richardson E, Pearce J, Mitchell R, Day P, Kingham S - BMC Public Health (2010)

Bottom Line: No significant associations between usable or total green space and mortality were observed after adjustment for confounders.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of GeoSciences, The University of Edinburgh, Edinburgh, UK.

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.

Conclusion: 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.

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Related in: MedlinePlus

Extract of the green space classification. An example of the green space classification for an area in the north east of Christchurch, New Zealand (approximate location indicated by dot on inset map). Map annotation gives the attribute information available for each area, showing that some are identifiable by name (e.g., Burwood Park) while others are identifiable only by the type of land use (e.g. 'park').
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Figure 2: Extract of the green space classification. An example of the green space classification for an area in the north east of Christchurch, New Zealand (approximate location indicated by dot on inset map). Map annotation gives the attribute information available for each area, showing that some are identifiable by name (e.g., Burwood Park) while others are identifiable only by the type of land use (e.g. 'park').

Mentions: An example of the classification is shown in Figure 2. The classification included green spaces ranging in size from large parks to the numerous small 'Recreation Reserves', some at less than 0.02 ha (200 m2). These small areas, found largely in built-up areas, were designated by the DOC for local recreation and sporting activities. CAUs in the main urban areas had a mean of 42% total green space coverage (range 0 to 100%), and 17% usable green space coverage (range 0 to 79%).


The association between green space and cause-specific mortality in urban New Zealand: an ecological analysis of green space utility.

Richardson E, Pearce J, Mitchell R, Day P, Kingham S - BMC Public Health (2010)

Extract of the green space classification. An example of the green space classification for an area in the north east of Christchurch, New Zealand (approximate location indicated by dot on inset map). Map annotation gives the attribute information available for each area, showing that some are identifiable by name (e.g., Burwood Park) while others are identifiable only by the type of land use (e.g. 'park').
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2875209&req=5

Figure 2: Extract of the green space classification. An example of the green space classification for an area in the north east of Christchurch, New Zealand (approximate location indicated by dot on inset map). Map annotation gives the attribute information available for each area, showing that some are identifiable by name (e.g., Burwood Park) while others are identifiable only by the type of land use (e.g. 'park').
Mentions: An example of the classification is shown in Figure 2. The classification included green spaces ranging in size from large parks to the numerous small 'Recreation Reserves', some at less than 0.02 ha (200 m2). These small areas, found largely in built-up areas, were designated by the DOC for local recreation and sporting activities. CAUs in the main urban areas had a mean of 42% total green space coverage (range 0 to 100%), and 17% usable green space coverage (range 0 to 79%).

Bottom Line: No significant associations between usable or total green space and mortality were observed after adjustment for confounders.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of GeoSciences, The University of Edinburgh, Edinburgh, UK.

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.

Conclusion: 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.

Show MeSH
Related in: MedlinePlus