Document Detail

Respiratory effects of 0.75 ppm sulfur dioxide in exercising asthmatics: influence of upper-respiratory defenses.
MedLine Citation:
PMID:  6832119     Owner:  NLM     Status:  MEDLINE    
To determine the influence of mouthpiece breathing on respiratory responses to sulfur dioxide (SO2), 23 young adult asthmatic volunteers were exposed in a chamber to 0.75 ppm SO2 during heavy exercise, once with breathing unencumbered and once while they wore noseclips and mouthpieces. These conditions (more severe than in typical ambient exposures) were deliberately chosen to produce significant physiological and clinical responses. Similar exposures to clean air served as controls. Exposure studies were separated by 1-week intervals and order was randomized. The protocol consisted of 10 min on a bicycle ergometer (mean load 650 kg-m/min, mean ventilation 40 liter/min), preceded and followed by response testing (body plethysmography, symptom questionnaires, and forced expiratory function tests; the last were performed only postexposure). During clean-air exposures, specific airway resistance (SRaw) and symptoms increased significantly, but no meaningful differences between mouthpiece breathing and unencumbered breathing were observed. Exposures to SO2 under these relatively severe conditions produced greater increases in SRaw than clean-air exposures regardless of the mode of breathing, but the excess increase was significantly greater with mouthpiece than with unencumbered breathing. Symptom changes and postexposure forced expiratory function showed qualitatively the same pattern of decrements with SO2 ad did SRaw, but the excess responses attributable to mouthpiece breathing did not attain statistical significance. Mouthpiece breathing can compromise upper-respiratory defenses against SO2 to the extent that responses are greater than with more natural breathing. The mode of breathing should be taken in account when applying laboratory human exposure data to air-quality risk assessment.
W S Linn; D A Shamoo; C E Spier; L M Valencia; U T Anzar; T G Venet; J D Hackney
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Publication Detail:
Type:  Clinical Trial; Controlled Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Environmental research     Volume:  30     ISSN:  0013-9351     ISO Abbreviation:  Environ. Res.     Publication Date:  1983 Apr 
Date Detail:
Created Date:  1983-05-27     Completed Date:  1983-05-27     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0147621     Medline TA:  Environ Res     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  340-8     Citation Subset:  IM    
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MeSH Terms
Air Pollutants / adverse effects*
Airway Resistance / drug effects
Asthma / diagnosis,  physiopathology*
Lung Volume Measurements
Pulmonary Ventilation
Respiration / drug effects*
Sulfur Dioxide / adverse effects*
Reg. No./Substance:
0/Air Pollutants; 7446-09-5/Sulfur Dioxide

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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