Wayne Watson loved extra-buttery microwave popcorn. In fact you might say the 53-year-old furniture salesman was a popcorn addict. For more than 10 years he microwaved two or three packages a day at work and in his Colorado home, often breaking open the bags to inhale the fragrance before diving in.

When Watson developed symptoms of a lung condition, the first doctor he consulted was puzzled. Watson didn’t smoke and had not been exposed to excessive amounts of mold or bird droppings–all of which can cause lung inflammation.