A crowded emergency department waiting room is more than unpleasant: New research suggests it's a serious hazard to your health.

Researchers recently looked at the difference in outcomes of patients who entered California hospitals through the emergency department in 2007. They looked at patients who visited the emergency department when it was "saturated," working at capacity and diverting ambulances elsewhere, and those who visited at less crowded times. 

They found, in a new Annals of Emergency Medicine study, that patients who came in through a crowded emergency department had 5 percent greater odds of dying in the hospital. Those patients also had longer hospital stays and higher costs, the same paper finds. 

There aren't many differences in the types of patients who visit the emergency department when its crowded or when its empty. Of those who came in to a saturated emergency room, 10.3 percent had congestive heart failure, compared to 10.4 percent of those arriving during less crowded hours. About half of the patients in each condition were white and just under a third were African-American.

The one big difference, this paper finds, is in the morality rate: Patients who came into a saturated emergency department had a 5 percent higher chance of dying in the hospital after their admission.

The researchers, lead by Oregon Health and Sciences University's Benjamin Sun, write that this likely has to do with a crowded emergency department challenging doctors' resources.

"ED crowding may reduce access through prolonged waiting times or through increased time to care as a result of longer ambulance transport after diversion," they write.  "A large literature has demonstrated the negative effect of ED crowding including delays in the
treatment of myocardial infarction, pneumonia, and painful conditions."

There's reason to think this is becoming an increasingly pressing problem: The average emergency room wait time increased 25 percent between 2003 and 2009, from 46.5 minutes to 58.1 minutes, according to the CDC.