H. Magnussen et al., EFFECTS OF ACUTE PASSIVE SMOKING ON EXERCISE-INDUCED BRONCHOCONSTRICTION IN ASTHMATIC-CHILDREN, Journal of applied physiology, 75(2), 1993, pp. 553-558
This study was designed to investigate the acute effects of environmen
tal tobacco smoke (ETS) in children with mild asthma during rest and e
xercise. We studied 13 children [8 males, 5 females; mean age 10 (rang
e 8-13) yr; mean forced expired volume in 1 s (FEV1) 93% (range 82-108
%) of predicted] with exercise-induced bronchoconstriction [46 +/- 4%
(SE) fall in FEV1 after exercise during cold air breathing]. Children
were exposed to ETS (20 ppm carbon monoxide) or ambient air (AA) for 1
h. During the first 54 min of exposure, children were at rest, and du
ring the last 6 min they exercised on a bicycle ergometer (2 W/kg body
wt). Spirometry was performed before and during exposure and after ex
ercise. Respiratory symptoms were recorded before and after exposures.
In seven children the experiments with AA and ETS were done in duplic
ate. FEV1 between 5 and 54 min of exposure at rest decreased by 3.2 +/
- 0.8% (SE) during AA and by 7.2 +/- 2.3% during ETS exposure compared
with preexposure values; the difference between AA and ETS was statis
tically significant (P = 0.04). The drop in FEV1 was achieved within 5
min and did not change with ongoing exposure. Analysis of individual
data revealed that the mean changes during ETS were mainly effected by
three children with a significant fall and one child with a significa
nt improvement in FEV1 (P < 0.05). Maximum postexercise fall of FEV1 w
as 25 +/- 4% after AA and 24 +/- 3% after ETS, which did not differ si
gnificantly. Upper and lower respiratory tract symptoms were not signi
ficantly different between exposures. We conclude that, in children wi
th mild asthma, short-term exposure to ETS can be associated with a tr
ansient fall in FEV1 in sensitive subjects but does not increase exerc
ise-induced bronchoconstriction. The acute airway response to exercise
can be increased significantly by cold and clean air compared with ai
r polluted by ETS.