Controlled exposures of young asthmatics to mixed oxidant gases and acid aerosol.
To help assess short-term respiratory responses to summertime air pollution, we exposed 24 asthmatic volunteers aged 11-18 in a chamber to respirable acid aerosol (mass median aerodynamic diameter 0.66 micron) plus 0.3 ppm nitrogen dioxide (NO2) plus 0.2 ppm ozone (O3). The aerosol contained available hydrogen ions (H-) at an average concentration of 2.6 mumol/m-, equivalent to 127 micrograms/m3 sulfuric acid (H2SO4); some H+ probably was in NH4HSO4 rather than H2SO4. The volunteers were exposed separately to O3/NO2 without acid and to clean air. Exposures lasted 90 min, including three 15-min exercise sessions with ventilation averaging 32 L/min, at 21 degrees C and 50% relative humidity. Asthma medications were withheld before and during exposures. Subjects gargled lemonade to minimize acid neutralization by oral ammonia (NH3). Exercise-induced bronchospasm was evident in all exposures. Differences in group mean lung function response among H2SO4/O3/NO2, O3/NO2, and clean-air exposures were not statistically significant. Individuals' measured oral NH3 concentrations or estimated inhaled doses of H2SO4 did not significantly predict their lung function changes. A few subjects showed unfavorable function changes during pollutant exposures, which might be chance occurrences or might indicate the existence of an acid-pollution-susceptible subgroup among young asthmatic subjects.
Linn
W S
WS
Environmental Health Service, Rancho Los Amigos Medical Center, Downey, CA 90242, USA.
Anderson
K R
KR
Shamoo
D A
DA
Edwards
S A
SA
Webb
T L
TL
Hackney
J D
JD
Gong
H
H
D000293:Adolescent; D000393:Air Pollutants / Q000494:pharmacology*; D001249:Asthma / Q000503:physiopathology*; D001273:Atmosphere Exposure Chambers; D002648:Child; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D010083:Oxidants, Photochemical / Q000494:pharmacology*; D012119:Respiration / Q000187:drug effects* / Q000502:physiology; D012129:Respiratory Function Tests; D013464:Sulfuric Acids / Q000494:pharmacology*
D000393:Air Pollutants; D010083:Oxidants, Photochemical; D013464:Sulfuric Acids