Abstract
Episodes of illness in separate arenas from carbon monoxide and nitrogen dioxide exposures are described. Excessive air concentrations of these gases resulted from the operation of ice resurfacing machines. Carbon monoxide concentrations up to 250 ppm following one episode and nitrogen dioxide concentrations up to 40 ppm following the other were found. All 45 ice arenas in Minnesota were visited subsequently to evaluate the variables responsible. Engine exhaust and ambient air data are presented. Infrared analyzer recordings of carbon monoxide concentrations in three arenas are shown. Possible methods of controlling exhaust gas problems are discussed.