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8 Carbon Monoxide
Pages 125-143

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From page 125... ... Doherty also reported that smoke, especially from the tips of cigarettes, is a source of CO that may lead to COHb concentrations as high as 10% to 15% in heavy smokers. In a study with 80 Boston police officers working in city street conditions, McFarland reported in 1973 that almost all the nonsmokers had COHb concentrations below 4%; for most of the smokers, it was below 6%, indicating much higher endogenous COHb concentrations in outdoor workers. Read the entire page →
From page 126... ... 0, value before CO exposure; M, equilibrium constant; PB, barometric pressure; P CO2, mean partial pressure of O2 in lung capillaries; ppm, parts per million; VA, alveolar ventilation rate; Vb, blood volume; VCO, rate of endogenous CO production. Source: Peterson and Stewart 1975, as cited by Penney 1999. Read the entire page →
From page 127... ... . Even though there were several conflicting reports on COHb concentrations higher than 5% affecting reaction time and hand-eye coordination, the lowest concentration was selected, because the author believed these impairments would interfere with the crew's ability to deal with a contingency event. Read the entire page →
From page 128... ... 17 1+ h (700 ppm Minimal effect on dark adaptation (driving Adult males 27 McFarland (1973) CO continuous) Read the entire page →
From page 129... ... 8.3 1 h (1,000 ppm for Effects of CO on muscle sympathetic nerve Adult males 12 Hausberg and Somers (1997) 30 min + 100 ppm for activity, forearm blood flow, blood pressure, 30 min continuous) Read the entire page →
From page 130... ... and has determined that, based on data from astronauts with spaceflight experience, there is no conclusive experimental evidence of cardiac dysrhythmias, manifestation of asymptomatic CV disease, or reduction in myocardial contractile function. The primary CV risks of spaceflight are compromised hemodynamic responses to central hypovolemia resulting in reduced orthostatic tolerance and exercise capacity. Read the entire page →
From page 131... ... Environmental Protection Agency; ERPG, emergency response planning guidelines; IDLH, immediately dangerous to life and health; IPCS, International Programme on Chemical Safety; NAAQS, National Ambient Air Quality Standard; NIOSH, NAC, National Advisory Committee; National Institute for Occupational Safety and Health; ; NRC, National Research Council; OSHA, Occupational Safety and Health Administration; PEL, permissible exposure limit; REL, recommended exposure limit; SEAL, submarine escape action level; TLV, threshold limit value; TWA, time weighted average; WHO, World Health Organization. Read the entire page →
From page 132... ... . They further postulated that modest increases in COHb concentrations, equivalent to that resulting from cigarette smoking, do not have appreciable acute effects on MSNA, BP, HR, or FBF and thus are unlikely to contribute to the acute sympathetic and hemodynamic effects of smoking in healthy humans. Read the entire page →
From page 133... ... Test subjects performed a randomized sequence of 5-min multilevel treadmill and hand-crank exercises on different days at less than 2% COHb and after attaining target levels of 5%, 10%, 15%, and 20% COHb. The team measured cardiac output, stroke volume, HR, cardiac contractility, and time to peak ejection time. Read the entire page →
From page 134... ... 134 SMACs for Selected Airborne Contaminants TABLE 8-3 Calculated COHb and Recorded CO Aboard Mir Spacestation Post-Fire Event Time, h CoHb, % Time, h CO, ppm 1 15 1.17 570 2 25 1.5 546 4 36 1.83 489 a 5 37 2.2 467 6 36 3.13 413 8 27.52 3.48 402 10 25.88 3.83 398 12 24.16 4.83 377 14 22.72 5.83 357 16 21.61 6.83 326 18 19.68 17.83 200 20 18.07 22.75 163 22 17.24 23.83 153 24 15.96 27.42 124 26 14.64 27.83 129 28 13.74 41.83 68 30 12.82 45.85 52 32 11.87 65.83 18 34 10.91 78.00 10 36 9.93 89.83 4 38 8.93 40 7.9 42 7.38 44 6.85 46 5.77 48 5.22 50 4.89 52 4.67 54 4.45 56 4.22 58 3.89 60 3.54 a Peak COHb at 37%; one of three crew members reported headache and nausea symptoms (James and Garcia 1994) Read the entire page →
From page 135... ... It also demonstrated that COHb concentrations of 24% do not increase HR and ventilation during normoxic and hyperoxic conditions. PROPOSED SMAC VALUES 2006 A review of available guidance levels, including NASA's original CO SMACs, has found that most levels set by various organizations do not align with NASA's mission objectives for protection of crew health. Read the entire page →
From page 136... ... values set by the NRC in 2007 for submariner protection most closely resemble the closed environment experienced during spaceflight, with the exceptions of the lack of microgravity and the allowance of smoking aboard their vessels. Research conducted after original publication of the CO SMAC, along with a review of older research, provides evidence for raising the current SMACs. Read the entire page →
From page 137... ... While NASA's inflight experience is not a conclusive scientific study, NASA has previously observed this COHb level (15%) as a no-reported-effect level in three crewmembers at 1 h pfe on Mir Spacestation. Read the entire page →
From page 138... ... The calculation of a 24-h exposure to 100 ppm results in a COHb concentration of 13.55%. No additional safety factors are applied because this is a NOAEL. Read the entire page →
From page 139... ... Whereas the formula provides point estimates, our calculations include spaceflight variables from actual COHb concentrations attained during long-term (6 month) missions, which preclude the use of any additional spaceflight factors. Read the entire page →
From page 140... ... 2008. National Ambient Air Quality Standards (NAAQS) Read the entire page →
From page 141... ... Pp. 67-102 in Emergency and Continuous Exposure Guidance Levels for Selected Submarine Contaminants, Vol. Read the entire page →
From page 142... ... 61-90 in Spacecraft Maximum Allowable Con centrations for Selected Airborne Contaminants, Vol. Read the entire page →
From page 143... ... , PL is barometric pressure minus vapor pressure of water (49) at body temperature (mmHg) Read the entire page →

From page 125...

... Doherty also reported that smoke, especially from the tips of cigarettes, is a source of CO that may lead to COHb concentrations as high as 10% to 15% in heavy smokers. In a study with 80 Boston police officers working in city street conditions, McFarland reported in 1973 that almost all the nonsmokers had COHb concentrations below 4%; for most of the smokers, it was below 6%, indicating much higher endogenous COHb concentrations in outdoor workers.

8 Carbon Monoxide Pages 125-143

8 Carbon Monoxide
Pages 125-143