Heat Exhaustion

Please take it easy in this dangerous heat, drink lots of
water, rest in cool areas, be alert for signs of heat stress, heat exhaustion,
and even heat stroke.  See http://www.bt.cdc.gov/disasters/extremeheat/heat_guide-page-3.asp for more details.  The Chicago area is in its 3rd day of 100+ degree heat.

From the CDC:
Heat exhaustion is a milder form of heat-related illness that
can develop after several days of exposure to high temperatures and inadequate
or unbalanced replacement of fluids.  Those most prone to heat exhaustion are
elderly people, people with high blood pressure, and people working or
exercising in a hot environment. 
Warning signs of heat exhaustion include the following:  
    The skin may be cool and moist, pulse rate will be fast and weak, 
    and breathing will be fast and shallow.

If heat exhaustion is untreated, it may progress to heat stroke.
Seek medical attention immediately if any of the following occurs:
    Symptoms are severe or the victim has heart problems or high blood pressure
Otherwise, help the victim to cool off, and seek medical attention if symptoms worsen or last longer than 1 hour.