Table 3.

Hazard ratios (HRs (95% CI)) for IHD associated with high air pollution levels (vs low) at home address among persons with different exercise/commuting habits

	Overall model with no interaction effects	Proportional hazard p value*	Adjusted† HRs in categories of high and low particle exposure
			Exercise in training clothes
			Never	Proportional hazard p-value*	≤Once/week	Proportional hazard p-value*	≥Twice/week	Proportional hazard p-value*
Low PM10‡	1		1		1		1
High PM10‡	1.14 (0.9 to 1.45)	0.55	1.21 (0.97 to 1.49)	0.71	1.25 (1.01 to 1.54)	0.45	0.68 (0.46 to 0.998)	0.50
Low PM2.5§	1		1		1		1
High PM2.5§	1.01 (0.8 to 1.28)	0.3	1.16 (0.94 to 1.44)	0.38	1.16 (0.95 to 1.43)	0.13	0.74 (0.51 to 1.09)	0.11
			Active commuting
			Non-active commuting		≤Two seasons of four		>Two seasons of four
Low PM10‡			1		1		1
High PM10‡			1.26 (1.03 to 1.54)	0.39	0.95 (0.7 to 1.29)	0.66	1.10 (0.86 to 1.41)	0.17
Low PM2.5§			1		1		1
High PM2.5§			1.24 (1.02 to 1.51)	0.11	0.91 (0.67 to 1.24)	0.84	1.01 (0.79 to 1.29)	0.04

*p-value of the Schoenfeld residual test of proportional hazards.

†Adjusted for sex, calendar year, education, smoking, alcohol intake, occupation, neighbourhood mean income, leisure time physical activity and active commuting.

‡Low PM₁₀: ≤9.6 µg/m³; high PM₁₀: >9.6 µg/m³.

§Low PM_2.5: ≤5.7 µg/m³; high PM_2.5: >5.7 µg/m³.

IHD, ischemic heart disease.