There was an interesting article, "A Survey of Carbon Monoxide and
Nitrogen Dioxide in Indoor Ice Arenas in Vermont," by Leonard J. Paulozzi
et al. in the Dec. 1993 issue of the Journal of Environmental Health.
(p. 23-25).
 
The researchers tested carbon monoxide and nitrogen dioxide measurements
in enclosed ice arenas in Vermont during high school hockey games.  They
tested 9 of the 11 indoor ice arenas in Vermont.  They found that a
significant number of the arenas had undesirable levels of either or both
of these air contaminants.  The authors recommend that electric ice
resurfacing machines be used, especially if the air contamination problem
can't be solved with ventilation.  The bibliography lists a number of
article about air quality problems in ice arenas, including several about
carbon monoxide poisonings.
 
Carol