Spacecraft Maximum Allowable Concentrations for Selected Airborne Contaminants Volume 5 (2008) / Chapter Skim
Currently Skimming:
3 Ammonia
3 Ammonia
Pages 48-61
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 48... ...
for ammonia were published in Volume 1 of this series, Spacecraft Maximum Allowable Concentrations for Selected Airborne Contaminants, for exposure durations of 1 h, 24 h, 7 d, 30 d, and 180 d (Wong 1994)
|
From page 49... ...
have indicated that ammonia concentrations were below the detection limit of 2 ppm for the new system. SUMMARY OF ORIGINAL APPROACH The SMACs for exposure durations of 1 h to 180 d were set by King-Lit Wong in 1994 (Table 3-1)
|
From page 50... ...
CHANGES IN FUNDAMENTAL APPROACHES RECOMMENDED BY THE NATIONAL RESEARCH COUNCIL The original SMACs for ammonia, set in 1994, were calculated using safety factors applied to a LOAEL. More recently, the National Research Council has recommended the use of a benchmark dose (BMD)
|
From page 51... ...
All 10 perceived discomfort ratings increased significantly during the exposure to 25 ppm of ammonia compared with the control exposure. However, no differences were observed in lung function or bronchial responsiveness when the exposure to fresh air (sham)
|
From page 52... ...
. The VAS scores at seven exposure durations ranging from 3 to 178 min for each subject for ammonia concentrations of 0, 5, and 25 ppm for each measured effect were entered into the BMDS version 1.4.1 software of the U.S.
|
From page 53... ...
The SMACs determined as described in the Rationale section below are listed in Table 3-5 RATIONALE FOR A 1,000-D SMAC AND REVISED 7-, 30-, AND 180-D SMACS Acceptable concentrations (ACs) were determined following the guidelines of the National Research Council's committee on Spacecraft Exposure Guidelines (NRC 2000)
|
From page 54... ...
Sundblad. TABLE 3-3 VAS Severity Score Averages for Exposures of 3 to 178 min Average VAS Scores Symptom 0 ppm 5 ppm 25 ppm Eye irritation 1.5 5.1 18 Nose discomfort 4.9 8.6 25 Throat discomfort 5.6 8.1 20 Breathing difficulty 2.5 2.5 14 Solvent smell 0.73 39 66 Headache 1.6 3.2 9 Fatigue 6.6 8 16 Nausea 1.2 1.7 3.7 Dizziness 1 2.4 5.8 Feeling of intoxication 0.86 2.6 5.6 Source: Calculated from raw data provided by B.M.
|
From page 55... ...
in pigs was also well done but was limited to a single exposure duration of 6 d and did not include an exposure to 0 ppm of ammonia. Because human data are preferable to animal data for setting human exposure limits, the data of Sundblad et al.
|
From page 56... ...
Average Score (3 to 178 min) Subject 0 ppm 5 ppm 25 ppm 0 ppm 5 ppm 25 ppm 0 ppm 5 ppm 25 ppm 2 0 0.9 10.4 0 55 49 0.14 0 3.9 3 1.5 19.6 20.4 1.5 23 71 2.5 2.6 2.4 4 4 7.3 38.4 3.1 4 48 3 4.4 11 5 6.9 7.6 23.1 0 64 76 5.9 4.1 20 6 0.4 5.4 43.7 0.43 67 82 0.29 1.7 8.1 8 1.7 1.9 20.4 1.1 23 79 1.1 0.86 2.3 9 1.4 1.9 5.0 0.57 49 67 3.6 4.6 9.1 10 0 0.0 14.8 0 36 72 0 5.1 20 11 0 1.0 13.1 0 26 51 0.14 0.43 1 12 0.1 3.1 17.3 0 19 79 0 2.1 23 13 2.1 9.1 8.4 2 74 34 2 10 3.4 14 0 3.4 5.6 0 27 82 0.14 2.9 3.9 Average 1.51 5.1 18.38 0.73 38.9 65.83 1.57 3.23 9.008 Standard deviation 2.09 5.44 12.13 1.01 22.3 16.16 1.88 2.72 7.855 Each score in the table is the average of the scores reported by an individual subject at exposure durations of 3, 28, 58, 88, 118, 148, and 178 min.
|
From page 57... ...
RfC values are meant to be protective of the entire population, including the elderly, children, and unusually sensitive individuals. SPACEFLIGHT EFFECTS None of the reported adverse effects of ammonia exposures are known to be affected by spaceflight other than transient nausea (spaceflight motion sickness)
|
From page 58... ...
Abbreviations: ACGIH, American Conference of Governmental Industrial Hygienists; ADJ, adjusted; EPA, U.S. Environmental Protection Agency; HEC, human equivalent concentration; IDLH, immediately dangerous to life or health; LOAEL, lowest-observedadverse-effect-level; NOAEL, no-observed-adverse-effect level; NIOSH, National Institute for Occupational Safety and Health; OSHA, Occupational Safety and Health Administration; PEL, permissible exposure limit; REL, recommended exposure limit; RfC, reference concentration; STEL, short-term exposure limit; TLV, threshold limit value; TWA, time-weighted average.
|
From page 59... ...
2004) SMAC 30 20 3 3 3 3 a AC values for 1 and 24 h were previously set by King Lit Wong in 1994 and were not changed because these short-term limits, unlike the limits for exposures of >1 d, are set to allow minor adverse effects, thereby permitting the crew to attempt to clean up or contain minor releases if they can do so within about 24 h.
|
From page 60... ...
Documentation of the Threshold Limit Values and Biological Exposure Indices, 7th Ed. American Conference of Governmental Industrial Hygienists, Cincinnati, OH.
|
From page 61... ...
Pp. 39-59 in Spacecraft Maximum Allowable Concentra tions for Selected Airborne Contaminants, Vol.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.