Air pollution exposure and lung function in highly exposed subjects in Beijing, China: a repeated-measure study

Table 2 Level of personal PM _2.5 , elemental carbon (EC), and elemental components of PM _2.5 during work hours on the examination days ^a

	Office workers								Truck drivers								Mean exposure difference (95% CI)^b
	(observations = 120)								(observations = 120)								Mean exposure difference (95% CI)^b
	N	Mean	SD	10pct	25pct	Median	75pct	90pct	N	Mean	SD	10pct	25pct	Median	75pct	90pct
PM_2.5	120	94.59	64.91	22.39	48.48	86.17	126.56	183.44	119	126.83	68.82	46.26	73.86	116.78	160.49	213.94	32.24 (15.19; 49.28)
EC	118	13.01	4.04	7.11	9.99	13.16	15.85	18.35	120	17.27	6.69	8.93	12.78	16.86	21.03	26.21	4.26 (2.84; 5.68)
K	118	0.76	0.77	0.18	0.27	0.56	0.82	2.07	120	1.31	1.07	0.34	0.44	0.89	2.06	2.81	0.55 (0.31; 0.79)
S	118	6.19	5.05	0.61	1.66	5.30	8.64	13.77	120	8.43	4.92	2.30	4.87	6.98	12.47	16.14	2.24 (0.97; 3.52)
Fe	118	0.38	0.21	0.17	0.24	0.34	0.44	0.69	120	1.01	0.64	0.38	0.50	0.82	1.34	1.75	0.63 (0.51; 0.75)
Si	118	0.79	0.53	0.28	0.45	0.68	1.03	1.43	120	2.37	1.76	0.64	0.82	2.09	3.54	4.13	1.58 (1.25; 1.91)
Al	118	0.54	0.25	0.23	0.37	0.50	0.70	0.86	120	1.36	0.93	0.44	0.59	1.29	1.86	2.32	0.82 (0.65; 0.99)
Zn	118	0.15	0.17	0.02	0.05	0.08	0.22	0.37	120	0.27	0.22	0.06	0.09	0.17	0.41	0.68	0.12 (0.07; 0.17)
Ca	118	0.32	0.18	0.15	0.19	0.28	0.41	0.54	120	2.09	2.2	0.29	0.4	1.58	3.08	4.52	1.76 (1.36; 2.17)
Ti	118	0.02	0.01	0.00	0.01	0.02	0.03	0.04	120	0.06	0.04	0.02	0.03	0.05	0.08	0.10	0.04 (0.03; 0.04)

^aMeasured during the work hours of examination days using light-weight personal monitors.
^bMean exposure levels of truck drivers – mean exposure levels of office workers.

ISSN: 1743-8977