This article gives no suggestions except for possible heat exhaustion, but from what I can tell from weather.com the high in Bowie MD today was only around 75!
http://www.weather.com/weather/today/Bowie+MD+USMD0045

Here is the news report saying that 3 dozen people fell ill at the Obama event and required treatment, fainting, and passing out.

http://www.wtop.com/?nid=25&sid=2072822

The White House schedule says the event took place around 3:15pm Eastern time today
http://www.whitehouse.gov/schedule/complete

puzzling.

W