No abstract

The average (all campaigns) outdoor concentration of PM(2.5) (28.3 μg m(-3)) measured by the cascade impactors was higher than the indoor value (22.3 μg m(-3)) and the corresponding average from the nearest fixed site monitor (23.6 μg m(-3)). Indoor and outdoor PM(2.5) concentrations exceeded the WHO recommended 24-h limit in 42% and 49% of the days measured, respectively. The correlation coefficient (r) between corresponding outdoor and indoor aerosol sizes increased with decreasing aerodynamic diameter of the collected particles (r = 0.32-0.87), suggesting a higher infiltration rate of fine and quasi-ultrafine particles. Principal component analysis revealed five factors explaining more than 82% of the data variability. The first two factors reflected a close association between outdoor and indoor fine and quasi-ultrafine particles confirming the hypothesis of high infiltration rate of particles from outdoors. The third factor indicated that human activity is the main source of indoor emission of coarse particles. The fourth factor involved only outdoor variables showing the resuspension of coarse ambient aerosol on dry and warm days without its seeming effect on the indoor coarse PM levels. Having in mind that high concentrations of both fine and coarse aerosol were frequently observed in the studied space, our results suggest that indoor exercise in polluted urbanized areas may increase the overall exposure and thus represent a potential health risk to young individuals during physical education at schools.

In periods of physical exercise, the greater the physical exertion, the greater the amount of air, including pollutants, which is inhaled, compared to sedentary activities. The school gym environment is in many aspects predisposed to high amounts of aerosol (particulate matter -PM) concentrations, which is cumulated in gym halls and re-suspended by exercising pupils during physical education (PE) lessons. PM concentrations (mainly its coarse particles) rise sharply according to the number of people exercising and the type of activity. The aim of our study was to estimate the aerosol exposure for 32 children exercising with increased ventilation in Prague primary school gyms (18 girls -10 to 14 years and 14 boys -10 to 13 years).The indirect method of transferring heart rate (HR) to minute ventilation (VE) through the exponential regression curve was used to measure pulmonary ventilation. HR was measured by sport-testers during PE lessons. Results of rest and ventilation load values were compared with the values of aerosol weight concentrations, measured continually by a photometer Dust Track and by the Personal Cascade Impactor Sampler.The study results indicate that during increased physical load inhalation exposure exceeds pollutant limit concentrations. We recommend that indoor areas, in which pupils exercise, should be cleaned with more care than places in which pupils are sedentary.