Table 2.

Adjusted incidence rate ratio of colon cancer by the health regions.

Health regiona	IRR	95% CI	P value	IRR	95% CI	P value
	Black carbon			Organic carbon
1	1.814	1.739–1.891	< 0.001	1.650	1.580–1.722	< 0.001
2	1.411	1.345–1.480	< 0.001	1.446	1.377–1.518	< 0.001
3	1.286	1.221–1.353	< 0.001	1.345	1.278–1.416	< 0.001
4	1.038	0.987–1.091	0.147	1.127	1.077–1.180	< 0.001
5	1.342	1.282–1.406	< 0.001	1.478	1.414–1.545	< 0.001
6	1.204	1.151–1.259	< 0.001	1.316	1.249–1.387	< 0.001
7	1.484	1.421–1.550	< 0.001	1.585	1.516–1.657	< 0.001
9	1.261	1.209–1.315	< 0.001	1.362	1.245–1.426	< 0.001
10	1.294	1.233–1.359	< 0.001	1.307	1.502–1.372	< 0.001
11	1.351	1.276–1.431	< 0.001	1.643	1.334–1.796	< 0.001
12	1.192	1.128–1.259	< 0.001	1.456	1.722–1.590	< 0.001
13	2.495	2.397–2.597	< 0.001	2.704	2.630–2.853	< 0.001

Health regiona	IRR	95% CI	P value	IRR	95% CI	P value
	Dust PM2.5			SO4
1	1.872	1.783–1.966	< 0.001	1.851	1.739–1.970	< 0.001
2	1.446	1.375–1.521	< 0.001	1.446	1.365–1.531	< 0.001
3	1.320	1.254–1.389	< 0.001	1.375	1.292–1.463	< 0.001
4	1.056	1.004–1.111	0.035	1.145	1.089–1.204	< 0.001
5	1.329	1.263–1.398	< 0.001	1.496	1.408–1.589	< 0.001
6	1.040	0.976–1.109	0.227	1.227	1.156–1.303	< 0.001
7	1.457	1.392–1.525	< 0.001	1.533	1.466–1.602	< 0.001
9	1.180	1.121–1.241	< 0.001	1.301	1.241–1.364	< 0.001
10	1.101	1.033–1.173	0.003	1.278	1.207–1.353	< 0.001
11	1.005	0.923–1.094	0.909	1.362	1.214–1.527	< 0.001
12	0.881	0.803–0.966	0.007	1.218	1.087–1.364	0.001
13	2.383	2.264–2.509	< 0.001	2.676	2.556–2.802	< 0.001

IRR incidence rate ratio, CI confidence interval.

^aReference: health region-specific incidence rate ratio are all expressed in relation to the lowest incidence rate ratio area (the health region 8).