Table 4.

Exposure to PM _{10 ,} PM _{2.5 ,} and PM _10–2.5 and risk of PD in the Nurses’ Health Study among non-movers, 1990–2008 (N = 80,544 women at baseline who did not move during the study)

	Multivariate a
	PY	Cases	RR	95% CI	P-trend
Quartiles of PM 10
3.8-21.0 μg/m3	395353	123	1.00	Ref
21.0– 24.3 μg/m3	395383	115	1.09	(0.84, 1.41)
24.3 – 28.3 μg/m3	395419	100	1.00	(0.76, 1.33)
28.3 – 88.3 μg/m3	395426	90	0.98	(0.76, 1.33)	0.92
Continuous^ PM 10	1581580	430	0.99	(0.89, 1.09)
Quartiles of PM 2.5
1.2-12.6 μg/m3	395343	110	1.00	Ref
12.6-15.0 μg/m3	395383	111	1.10	(0.83, 1.45)
15.0-17.4 μg/m3	395409	121	1.25	(0.94, 1.65)
17.4-73.9 μg/m3	395446	88	1.11	(0.81, 1.52)	0.43
Continuous^ PM 2.5	158446	430	1.08	(0.81-1.45)
Quartiles of PM 10–2.5
0-7.2 μg/m3	395375	132	1.00	(Ref)
7.2-9.2 μg/m3	395394	106	0.93	(0.71, 1.21)
9.2-12.0 μg/m3	395397	96	0.90	(0.68, 1.20)
12.0-67.1 μg/m3	395395	96	0.90	(0.63, 1.28)	0.64
Continuous^ PM 10–25	1937996	430	0.95	(0.85-1.05)

PY: person years; RR: relative risk; 95% CI: 95 percent confidence interval.

^aadjusted for age, smoking, region (northeast, midwest, west, and south), population density, caffeine intake (<100 mg/day vs. over 100 mg/day) and ibuprofen use (ever/never user).

^per 10 μg/m³.