Carbon Monoxide Exposure
Trends in U.S. Air CO Levels:
Figure 3-6. Composite average of the annual second highest 8 hr. Carbon Monoxide concentrations for rural, suburban, and urban sites, 1988 - 1997.
Source: EPA. Air Quality Criteria for Carbon Monoxide, National Center for Environmental Assessment, 2000
...... last changed 06/01/04
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