The National Academies Press

Currently Skimming:

3 Carbon Dioxide
Pages 46-66

The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.

From page 46... ... , 24-h, and 90-day exposure guidance levels for CO2. The subcommittee's recommendations for CO2 exposure levels are provided at the conclusion of this chapter along with a discussion of the adequacy of the data for defining those levels and the research needed to fill the remaining data gaps. Read the entire page →
From page 47... ... . SUMMARY OF TOXICITY The information below was taken largely from a more comprehensive review, Spacecraft Maximum Allowable Concentrations for Selected Airborne Contaminants, Volume 2 (NRC 1996) Read the entire page →
From page 48... ... . It was also noted in 10 of 12 subjects exposed at 7,000 Read the entire page →
From page 49... ... . Similarly, there were no symptoms reported in six subjects exposed to CO2 at 20,000 ppm for 30 days or 29,000 ppm for 8 days and made to do 10 min of exercise twice a week at a workload of 150 watts (Guillerm and Radziszewski 1979; Radziszewski et al. Read the entire page →
From page 50... ... reported that for 16 resting subjects exposed to CO2 at 10,000-80,000 ppm for 17-32 min, headaches developed only at concentrations that were $50,000 ppm; however, the headache could be intense. At 28,000 ppm for 1 h of strenuous steady-state exercise, occasional mild headaches were noted among four subjects (Sinclair et al. Read the entire page →
From page 51... ... Exposures to CO2 at concentrations much higher than those in ambient air lead to increased partial pressure of CO2 in alveoli and blood. That causes a lowering of blood pH, which is eventually buffered by blood proteins and bicarbonate. Read the entire page →
From page 52... ... Guillerm and Radziszewski (1979) reported a 10% reduction in hematocrit and a 9% reduction in red blood cell count in subjects exposed to CO2 at 20,000 ppm for 30 days. Read the entire page →
From page 53... ... Brown (1930) studied five subjects exposed to CO2 concentrations that ranged from 41,000 ppm to 53,000 ppm for 8 h. Read the entire page →
From page 54... ... (1967) reported no effects on hand steadiness, vigilance, auditory monitoring, memory, or arithmetic and problem solving performance. Read the entire page →
From page 55... ... . A CO2 exposure at 30,000 ppm for 8 days in a working submarine crew (unknown number of subjects) Read the entire page →
From page 56... ... . These results are not considered to be relevant for setting exposure guidelines because of the extremely high exposure concentrations used. Read the entire page →
From page 57... ... . CO2 undergoes catalysis by the enzyme carbonic anhydrase in red blood cells to form carbonic acid, which is then ionized to bicarbonate (Baggott 1982) Read the entire page →
From page 58... ... . INHALATION EXPOSURE LEVELS FROM THE NRC AND OTHER ORGANIZATIONS A number of organizations have established or proposed acceptable inhalation exposure limits or guidelines for CO2. Read the entire page →
From page 59... ... (1997) found asymptomatic decrements in stereoacuity and motion perception in a total of six subjects exposed at 25,000 ppm for durations of about 1 h. Read the entire page →
From page 60... ... NRC Recommended Exposure Level Current Proposed Values (ppm) EEGL 1h 40,000 30,000 25,000 24 h 40,000 15,000 25,000 CEGL 90 days 5,000 7,000 8,000 Abbreviations: CEGL, continuous exposure guidance level; EEGL, emergency exposure guidance level; h, hour; NRC, National Research Council; ppm, parts per million. Read the entire page →
From page 61... ... found no symptoms in six subjects exposed to CO2 at 20,000 ppm for 30 days, although minute-volumes increased about 40% during the first several days of the study. Sinclair et al. Read the entire page →
From page 62... ... Presentation at the First Meeting on Emergency and Continuous Exposure Guidance Levels for Selected Submarine Contaminants, January 23, 2003, Washington, DC. Consolazio, W.B., M.B. Read the entire page →
From page 63... ... Presentation at the First Meeting on Emergency and Continuous Exposure Guidance Levels for Selected Submarine Contaminants, January 23, 2003, Washington, DC. Hamilton, A., and H.L. Read the entire page →
From page 64... ... 1948. Chronic carbon dioxide poisoning experimental studies. Read the entire page →
From page 65... ... 1961. A concept of triple tolerance limits based on chronic carbon dioxide toxicity studies. Read the entire page →
From page 66... ... 1979. Effect of prolonged exposure to elevated carbon monoxide and carbon dioxide levels on red blood cell parameters during submarine patrols. Read the entire page →

From page 46...

... , 24-h, and 90-day exposure guidance levels for CO2. The subcommittee's recommendations for CO2 exposure levels are provided at the conclusion of this chapter along with a discussion of the adequacy of the data for defining those levels and the research needed to fill the remaining data gaps.

3 Carbon Dioxide Pages 46-66

3 Carbon Dioxide
Pages 46-66