For me the helmets are the most dangerous part of football these days. As much as they protect players, they also cause so many serious injuries. I've been nervous for awhile every time I see a player hit someone or get hit by a helmet. Even though this seems like a freak occurrence, in the end it's still caused by a hit by a helmet.
On the positive/ironic side, there are not many more likely places to survive cardiac arrest than a football field, with all the doctors and emergency medical equipment on standby and plenty of people who know what to look for and what to do.