Particulate matter and gases such as carbon monoxide and nitrogen dioxide, which are abundant in indoor ice arenas, and chlorine from swimming pools may act as allergic ???triggers??? and may exacerbate bronchospasm in athletes who are predisposed to EIB. Helenius and Haahtela34 showed a 96-fold greater risk of asthma in atopic swimmers when compared to nonatopic control subjects when atopy and sw