Just when you thought it was safe to go back to the ice rink . . .

March 8, 2012, 8:50 pm

Exposure to Nitrogen Dioxide in an Indoor Ice Arena — New Hampshire, 2011. MMWR 2012 March 2;61:139-142.

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This report — from the Centers for Disease Control and Prevention — describes a mass exposure to nitrogen dioxide (NO2) that occurred among hockey players and coaches at a school hockey arena when the ventilation system malfunctioned. The source of the NO2 was identified as a propane-powered ice resurfacing machine.

The index case was a 19-year-old previously healthy male who developed sudden onset, cough, dyspnea, and hemoptysis who had practiced with his hockey team and the rink the previous evening. On exam he had bilateral basilar rales and decreased oxygen saturation (88-91%) on room air. Chest CT showed bilateral infiltrates and nodules.

Public health investigation determined that a yellow haze was noted on the ice at the practice session. Interviews with players and coaches present at the practice session — as well as the workers who did the resurfacing — identified 31 cases among 44 exposed persons. A case was defined as: “onset of cough, hemoptysis, chest pain, chest tightening, shortness of breath, headache, dizziness, nausea, or vomiting within 48 hours of being on the ice [during the 22 hours after resurfacing]”. Most common symptoms were cough, shortness of breath, and chest tightness.

The authors note that toxic levels of nitrogen dioxide in ice arenas can result from malfunctioning propane-fueled ice resurfacing equipment or ventilation symptoms. The risk of NO2 exposure can be minimized or eliminated if ice arenas monitor levels of NO2 , or utilize electric ice resurfacing equipment.

Nitrogen dioxide is a yellow or reddish brown gas that irritates the upper and lower respiratory tracts. However, it is poorly water soluble, and therefore causes little irritation or the upper respiratory tract at low levels. Therefore, it has poor warning properties. The index case in this series illustrates a characteristic presentation, with onset of chemical pneumonitis and hypoxemia that can be delayed for up to 24 hours. Rarely, patients who have been exposed to NO2 can go on to develop life-threatening bronchiolitis obliterans.

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