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document
Acute exposure to acid fog : influence of breathing pattern on effective dose . Concern about the possible adverse health effects of acid fog has been fed by two observations : air pollution disasters earlier in this century were typically associated with fog , and current samples of fog water can be strongly acid . To study the acute effects of acid fog on the lung , the authors generated a monodisperse 10 microM MMAD aerosol of H2SO4 with a pH of 2.0 and a nominal concentration of 500 micrograms/m3 . They exposed seven healthy young men on alternate days to acid or control equiosmolar NaCl aerosol during 40 min of resting ventilation and 20 min of exercise ; the latter was sufficiently intense to induce oronasal breathing . Exposure was by means of a head dome , a head-only exposure device that permitted continuous measurement ( unfettered breathing ) of Vr , f , VE , and the onset and persistence of oronasal breathing . In this article the authors compare the relative importance of parameters contributing to the between-subject variability in estimated hydrogen ion dose to the lower airways ( H+LAW ) , based on analysis of variance . Physiologic parameters accounted for 70 % of the variability , of which 34 % was due to differences in duration of oronasal breathing ( tON ) and 36 % to differences in ventilation rate during oronasal breathing ( VE ( ON ) ) ; inhaled hydrogen ion concentration [ H+ ] , the environmental parameter , contributed only 30 % . Minute ventilation at the time of transition from nasal to oronasal breathing varied significantly among subjects even if normalized to FVC , an index of lung size .
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Intervention_Pharmacological
monodisperse 10 microM MMAD aerosol of H2SO4
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Intervention_Other
nominal concentration
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Intervention_Pharmacological
acid
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Intervention_Pharmacological
control
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Intervention_Control
equiosmolar NaCl aerosol
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Outcome_Physical
effective dose
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Outcome_Adverse-effects
adverse health effects
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Outcome_Physical
oronasal breathing
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Outcome_Physical
oronasal breathing
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Outcome_Physical
lower airways
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Outcome_Physical
duration of oronasal breathing ( tON )
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Outcome_Physical
ventilation rate during oronasal breathing ( VE ( ON ) ) ; inhaled hydrogen ion concentration [ H+ ]
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Participant_Condition
exposure to acid fog :
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Participant_Sample-size
seven
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Participant_Age
healthy young men