INDOOR MOTOCROSS COMPETITIONS - AIR-QUALITY EVALUATION

Concentrations of carbon monoxide (CO) and of nitrogen dioxide (NO2) w ere monitored continuously during a motocross competition in an indoor skating rink with the help of direct reading apparatus in five areas of the building. initially, exposure limits were set at 50 and 2 ppm, respectively, for CO and NO2. If excesses were to occur, activities wo uld be interrupted until the levels decreased to under 25 ppm for CO a nd 0.5 ppm for NO2. NO2 was not detected during the event. However, CO concentrations generated by motorcycles required that competitions be interrupted seven times. The analysis of measurements obtained from e ach monitor indicated that concentrations varied significantly among s ampling stations. Modelling of CO concentrations using a covariance an alysis revealed that the initial concentration, the event duration, th e motor size, and especially the number of motorcycles on the track we re all positively associated with levels of CO at the end of the race. Time-weighted average CO concentrations for the whole evening slightl y exceeded reference limits generally accepted for the protection of p ublic health.