During a short period of increased air pollution in a polluted area in the Netherlands, a majority of the inhabitants showed a lower VC and FEV1 value than during a period of extremely low pollution. This may be due to a temporary decrease in the ventilatory function in response to a temporary increase in air pollution. Persons who showed the greatest "decrease" in the VC and/or FEV1 had a slightly higher prevalence of chronic non-specific lung disease (CNSLD) than did those who had a slight or no decrease in VC and FEV1. The studies will be continued in order to determine whether the groups will show different repiratory disease patterns in the future. In studies on long-term effects of exposure to air pollution, one must consider the possibility that short-term effects may influence the results of the lung function measurements. It is always important, therefore, to include a questionnaire on respiratory symptoms in such studies, since it is unlikely that short periods of air pollution influence the prevalence of chronic respiratory symptoms.

Adolescent↗

PubMedDate not supplied

Changes in functional residual capacity during exercise in patients with exercise-induced asthma.

Forty-eight patients with a history of exercise-induced asthma were exercised on ambient breathing (T = 18-20 degrees C, relative humidity = 45-55%). There were 19 responders and 29 non-responders according to post-exercise spirometry. During the first minutes of exercise at a workload of 25-50 W, the functional residual capacity (FRC) was measured by a rebreathing technique. There was a significant increase in FRC in responders (p less than 0.025). A loose though significant correlation was found between the rise in FRC during exercise and the fall in forced expiratory volume in one second (FEV1) after exercise (r = -0.429, p less than 0.005). The effects of a sympathomimetic drug were studied in five responders submitted to a second exercise test 4 h after the first one. Spirometry returned to normal but FRC remained high between both tests. During the second test neither spirometry nor FRC changed. The results suggest that different mechanisms may be responsible for changes in FRC and in maximal expiratory flow in exercise-induced broncho constriction.

Adolescent↗