Very few firefighters used respirators or other types of breathing protection in the early days after the September 11 attack on the World Trade Center, when the air was at its worst, according to reports on the firefighters' injuries and illnesses published by the Centers for Disease Control and Prevention, and in the New England Journal of Medicine.

In the first hours after the attack, most of the thousands of rescuers and workers rushed into the clouds of dust and smoke without much regard for their lungs, the reports say, based on surveys of the workers.