WASHINGTON - Hockey players and figure skaters may be facing an unexpected risk after intermissions - inhaling fumes from those colorful ice-resurfacing machines.
Gasoline- and propane-powered ice- surfacing machines may produce hazardous levels of nitrogen dioxide in rinks, according to a study by Harvard University researchers.
Jonathan Levy, one of the researchers, likened the situation to letting your car run in a closed garage.
"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," he said.
The solution, he said, 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."
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 ice 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, said Levy, a doctoral student who took part in the research, reported in this month's 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.
The researchers studied 19 ice rinks in the Boston area over three years and found that rinks with propane-powered 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 parts per billion for those with electric machines.
Studies have found increased levels of respiratory illness in people with chronic exposure to 100 parts per billion of the gas, the researchers said.
Using electric machines can solve the problem, but buying a new machine can cost up to $100,000, Levy said, so the more practical answer may be better ventilation as well as making sure the machines are tuned to reduce emissions.