Table 1
Descriptive summary statistics for all variables. Note: ppb = parts per
billion; IRSAD = index of relative socio-economic advantage and disadvantage;
IRSD = index of relative socio-economic disadvantage; IER = index of
economic resources; IEO = index of education and occupation.
Variable (units) Mean S.D. Min. Max.
Annual average NO2 2006–11
(ppb)
8.0 2.8 2.3 30.1
Non-Indigenous population
density (persons/km2)
Indigenous population density
(persons/km2)
Total population density
(persons/km2)
Percent non-Indigenous (%)
Percent Indigenous (%)
IRSAD score
IRSD score
IER score
IEO score