ABSTRACT
Carbon Monoxide. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.3 Trends in Carbon Monoxide Emissions and Ambient Air Quality . . . . . . . 8 2.4 Human Exposure to Carbon Monoxide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 2.5 Microenvironmental Exposures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.5.1 Residential Exposures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 2.5.1.1 Nonfatal Exposures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 2.5.1.2 Fatal Exposures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.5.2 Occupational Exposures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 2.5.3 Shopping Center Exposures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 2.5.4 Recreational Exposures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.5.4.1 Exposures on Recreational Vehicles . . . . . . . . . . . . . . . . . . . . 23 2.5.4.2 Exposures at Indoor Sporting Events . . . . . . . . . . . . . . . . . . . 24
2.5.5 Commuter Exposures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 2.5.5.1 Defective Exhaust Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 2.5.5.2 Parking Garages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 2.5.5.3 Service Stations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 2.5.5.4 Drive-Up Facilities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 2.5.5.5 Airbag Deployment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 2.5.5.6 Motor Vehicle Emission Standards. . . . . . . . . . . . . . . . . . . . . . 30
2.6 Exposure to Methylene Chloride. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 2.6.1 Nonoccupational Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 2.6.2 Occupational Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
2.7 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 2.8 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
8417: “8417_c002” — 2007/9/11 — 12:16 — page 6 — #2
Carbon monoxide (CO) is a gas commonly produced by incomplete combustion of fuels containing carbon atoms. Many people use these fuels (i.e., coal, gasoline, kerosene, natural gas, oil, propane, and wood) around the globe. As a result, CO is ubiquitous in the atmosphere. However, without sophisticated instruments, a person is unable to detect CO, because the gas is not irritating and has no color, odor, or taste. Moreover, the gas is a potential health hazard, because exposure to CO can starve critical body organs, especially the brain and heart, of oxygen. Once inside the lungs, CO molecules pass easily into the bloodstream and compete with oxygen for hemoglobin (Hb) in the red blood cells. About 95% of the absorbed CO readily binds with Hb to form carboxyhemoglobin (COHb), because the affinity of Hb for CO is over 200 times stronger than it is for oxygen. Thus, the percentage of total Hb in the blood that is in the form of COHb is a biomarker of CO exposure.1
