Eating too fast, or impaired breathing. If you have a deviated septum or sinus congestion (from allergies, for example), you need to breathe through your mouth instead of your nose, which is more likely to pick up bits of food in the airstream. Near the end of her life, my mom was averaging one bout of pneumonia a month from aspirated food. That was because of severe osteoporosis, which made her esophagus not work right.