Neighbourhood walkability, road density and socio-economic status in Sydney, Australia.
BACKGROUND
Planning and transport agencies play a vital role in influencing the design of townscapes, travel modes and travel behaviors, which in turn impact on the walkability of neighbourhoods and residents' physical activity opportunities. Optimising neighbourhood walkability is desirable in built environments, however, the population health benefits of walkability may be offset by increased exposure to traffic related air pollution. This paper describes the spatial distribution of neighbourhood walkability and weighted road density, a marker for traffic related air pollution, in Sydney, Australia. As exposure to air pollution is related to socio-economic status in some cities, this paper also examines the spatial distribution of weighted road density and walkability by socio-economic status (SES).


METHODS
We calculated walkability, weighted road density (as a measure of traffic related air pollution) and SES, using predefined and validated measures, for 5858 Sydney neighbourhoods, representing 3.6 million population. We overlaid tertiles of walkability and weighted road density to define "sweet-spots" (high walkability-low weighted road density), and "sour- spots" (low walkability-high weighted road density) neighbourhoods. We also examined the distribution of walkability and weighted road density by SES quintiles.


RESULTS
Walkability and weighted road density showed a clear east-west gradient across the region. Our study found that only 4 % of Sydney's population lived in sweet-spot" neighbourhoods with high walkability and low weighted road density (desirable), and these tended to be located closer to the city centre. A greater proportion of neighbourhoods had health limiting attributes of high weighted road density or low walkability (about 20 % each), and over 5 % of the population lived in "sour-spot" neighbourhoods with low walkability and high weighted road density (least desirable). These neighbourhoods were more distant from the city centre and scattered more widely. There were no linear trends between walkability/weighted road density and neighbourhood SES.


CONCLUSIONS
Our walkability and weighted road density maps and associated analyses by SES can help identify neighbourhoods with inequalities in health-promoting or health-limiting environments. Planning agencies should seek out opportunities for increased neighbourhood walkability through improved urban development and transport planning, which simultaneously minimizes exposure to traffic related air pollution.
South West Sydney Clinical School, UNSW Australia, Sydney, NSW, Australia. christine.cowie@sydney.edu.au.|Ingham Institute of Applied Medical Research, Sydney, NSW, Australia. christine.cowie@sydney.edu.au.|Woolcock Institute of Medical Research, University of Sydney, Sydney, NSW, Australia. christine.cowie@sydney.edu.au.
Christine T
CT
Cowie
Prevention Research Collaboration, Sydney School of Public Health, University of Sydney, Sydney, NSW, Australia.
Ding
D
Ding
University Centre for Rural Health, University of Sydney, Lismore, NSW, Australia.
Margaret I
MI
Rolfe
Public Health Unit, Illawarra Shoalhaven Local Health District, Wollongong, NSW, Australia.|Sydney School of Public Health, University of Sydney, Sydney, NSW, Australia.|Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia.|Graduate School of Medicine, University of Wollongong, Wollongong, NSW, Australia.
Darren J
DJ
Mayne
South West Sydney Local Health District, Sydney, NSW, Australia.|School of Public Health and Community Medicine, UNSW Australia, Sydney, NSW, Australia.
Bin
B
Jalaludin
Prevention Research Collaboration, Sydney School of Public Health, University of Sydney, Sydney, NSW, Australia.
Adrian
A
Bauman
University Centre for Rural Health, University of Sydney, Lismore, NSW, Australia.
Geoffrey G
GG
Morgan
D000393:Air Pollutants / Q000032:analysis; D001315:Australia; D002947:Cities; D006801:Humans; D018986:Motor Vehicles; D009585:Nitrogen Dioxide / Q000032:analysis; D012111:Residence Characteristics; D012923:Social Class; D014504:Urban Health; D014505:Urban Population; D016138:Walking
D000393:Air Pollutants; D009585:Nitrogen Dioxide
Air pollution; Health; Neighbourhood; Nitrogen dioxide; Traffic; Transport; Walkability