Table 2.

Ambient Carbon Monoxide Concentrations^a and Study Participants’ Estimated Carbon Monoxide Exposures and Carboxyhemoglobin Concentrations (n = 708), Western Washington, 1996–2004

	Mean	Minimum	Percentile				Maximum
			25th	50th	75th	95th
Local monthly CO concentration, ppm	1.08 (0.4)b	0.38	0.80	1.08	1.38	1.87	2.64
Estimated CO exposure in month of blood draw, ppm	1.00 (0.40)	0.12	0.71	0.97	1.28	1.70	2.14
Estimated CO exposure in trimester of blood draw, ppm	1.01 (0.39)	0.16	0.73	0.99	1.27	1.68	2.07
Carboxyhemoglobin level, % hemoglobin	0.93 (0.43)	0.17	0.72	0.85	1.04	1.55	5.92

Abbreviation: CO, carbon monoxide.

^aLocal concentrations measured at 15 monitoring sites.

^bNumbers in parentheses, standard deviation.