Effects of particulate air pollution on blood pressure in a highly exposed population in Beijing, China: a repeated-measure study

Table 2 Levels of personal exposure to PM_2.5 and Elemental Carbon (EC) during work hours, and of ambient PM₁₀ and outdoor temperature on the days before examination

	Time window	Office Workers								Truck Drivers
		N	Mean	SD	10pct	25pct	Median	75pct	90pct	N	Mean	SD	10pct	25pct	Median	75pct	90pct	p-value
Personal PM _2.5 ^a (μg/m ³ ) on the examination days, from personal monitors
	8 hours	120	94.6	64.9	22.4	48.5	86.2	126.6	183.4	119	126.8	68.8	46.3	73.9	116.8	160.5	213.9	<0.001
Personal EC ^a (μg/m ³ ) on the examination days, from personal monitors
	8 hours	118	13.0	4.0	7.1	10.0	13.2	15.8	18.4	120	17.2	6.6	9.2	12.9	16.7	20.9	26.1	<0.001
Ambient PM ₁₀ (μg/m ³ ) from ambient monitors on the days prior to the study days
	1-day mean	120	121.5	47.8	72.0	82.0	118.0	146.0	186.0	120	119.5	51.2	64.0	82.0	118.0	142.0	188.0	0.76
	2-day mean	120	121.6	38.0	74.5	93.0	125.0	146.0	173.0	120	119.3	40.3	66.0	91.0	120.0	144.0	157.0	0.64
	5-day mean	120	119.5	26.9	80.7	105.6	119.6	138.0	148.8	120	118.2	25.6	81.0	96.8	119.6	136.8	144.0	0.69
	8-day mean	120	119.5	23.0	84.9	101.8	119.9	141.5	146.5	120	120.2	21.5	95.6	102.8	120.4	139.0	146.3	0.81
Outdoor temperature (°C) on the days prior to the study days
	1-day mean	120	25.1	2.7	22.0	23.0	26.0	28.0	29.0	120	25.3	2.6	22.0	23.0	26.0	28.0	29.0	0.75
	2-day mean	120	25.2	2.3	22.0	23.0	25.5	27.5	28.0	120	25.0	2.7	22.0	23.0	25.3	27.0	28.0	0.56
	5-day mean	120	25.1	1.8	22.6	23.6	25.6	26.4	27.2	120	24.9	1.7	22.6	23.2	25.4	26.4	27.0	0.30
	8-day mean	120	25.0	1.4	23.1	24.0	24.6	26.4	27.0	120	24.9	1.4	23.1	23.6	24.5	26.3	26.9	0.34

^aMeasured during the work hours of examination days using light-weight personal monitors.

ISSN: 1476-069X