We conclude that reduced cyclone frequency in a
future warmer climate will lead to an increase in the severity
of summertime pollution episodes in the northeastern and
midwestern United States. Although the GCM used in our
analysis is relatively coarse, the decrease in cyclone frequency
and implication for air quality appears to be a robust
result. It is well established that cyclones play a critical role
in ventilating pollution from these regions. There is also
compelling evidence that the frequency of these cyclones
has been decreasing over the past decades