Table 2.

Correlations between participant air pollution estimates and potential confounders

	BS 1971	SO2 1971	BS 1981	SO2 1981	BS 1991	SO2 1991	PM10 2001	Age	Population density	RR lung cancer
BS 1971 n=367 658	1.000
SO2 1971 n=367 658	0.730	1.000
BS 1981 n=305 471	0.696	0.531	1.000
SO2 1981 n=305 471	0.519	0.720	0.762	1.000
BS 1991 n=259 649	0.651	0.405	0.769	0.538	1.000
SO2 1991 n=259 649	0.645	0.452	0.750	0.600	0.866	1.000
PM10 2001 n=221 148	0.195	0.411	0.200	0.413	0.077	0.190	1.000
Age n=367 658	−0.002	0.012	−0.020	−0.005	−0.035	−0.034	−0.014	1.000
Population density n=367 658	0.441	0.689	0.252	0.438	0.044	0.107	0.380	0.031	1.000
RR lung cancer n=221 148	0.059	−0.162	0.010	−0.202	0.007	0.047	−0.191	0.004	−0.150	1.000

Population Density—population density 1 km grid. Source: Office for National Statistics Longitudinal Study (authors’ own work).

BS, black smoke.