Abstract

Objective: To investigate how daily variations in ambient air pollution, especially in particles, during the cold of winter affect repeated measurements of baseline lung function and exercise induced bronchial responsiveness among primary school children with chronic respiratory symptoms.

Methods: During alternate school weeks (mamimum five) from February to April 1994, 33 children took part in exercise challenge tests (n=141 tests). The exercise challenges were conducted outdoors in a school yard in the centre of Kuopio, Finland. Spirometric lung functions were measured indoors before the exercise, and 3 and 10 minutes after. Daily mean concentrations of PM₁₀, black smoke (BS), NO₂, CO, SO₂, and particle size and numbers were monitored at a nearby fixed monitoring site.

Results: Daily variations in ambient air pollution were not associated with enhanced bronchial responsiveness. However, increased concentrations of BS, PM₁₀, particle numbers, NO₂, and CO were consistently associated with an impairment of baseline lung functions. The reductions in forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV₁) were 0.5% and 0.6%, respectively, for each 10 μg/m³ increase in BS (lag 2).

Conclusion: Particles derived from combustion affect baseline lung function rather than bronchial responsiveness among children with chronic respiratory symptoms.