WASHINGTON AP Ice rink spectators may want to think twice before giving a round of applause to the guy driving the colorful ice resurfacing machine. His work may be hazardous to their health. A study by Harvard University researchers concludes that gasoline- and propane-powered ice surfacing machines may produce hazardous levels of nitrogen dioxide in rinks. It's sort of like running your car in the garage said Jonathan I. Levy one of the researchers. ``If you leave the engine on in the garage for a period of time you know that the pollution levels rise. Obviously an ice rink is larger ... but it is a similar idea.'' The solution is increased ventilation. ``Basically ventilation levels in ice rinks tend to be not that high because if you bring in too much outside air you have trouble keeping ice quality'' Levy said. The resurfacing machines are best known by their brand names such as Zamboni Olympia and others. They smooth the ice and spread a film of water that quickly freezes improving the surface between periods of hockey games and in the intermissions at ice shows. The increased levels of nitrogen dioxide immediately after the machines operate have led to reports of respiratory problems including coughing tightness of the chest and shortness of breath the researchers said. In one case a group of Minnesota hockey players had breathing problems a half hour after the ice was resurfaced. ``The jury is out'' as to whether there is long-term damage Levy said. His research was reported in the December edition of the American Journal of Public Health. There is some evidence that chronic exposure to high levels of nitrogen dioxide leads to a greater risk of respiratory infection in children and worsens asthma symptoms'' Levy said in an interview. The researchers studied 19 ice rinks in the Boston area for three years and found that rinks with propane-powered ice resurfacing machines had average nitrogen dioxide concentrations of 206 parts per billion. The average was 132 parts per billion for rinks with gasoline machines and 37 ppb for those with electric machines. Studies have found increased levels of respiratory illness in people with chronic exposure to 100 ppb of the gas the researchers said. Using electric ice resurfacing machines can also help solve the problem but buying a new machine can cost up to dlrs 100000 Levy said so the more practical answer may be better ventilation as well as making sure the machines are tuned to reduce emissions. APW19981201.0044.txt.body.html APW19981201.0939.txt.body.html