<<Disclaimer: Verify this information before applying it to your situation.>> These facts may seen as very restricted for a person on the GF diet. But with information, we can determine our lifestyle. When unknown problems develop, we may have a clue as to the source of contamination. Grain dust in the air should also be considered in discussion with companies that process multiple grains. Two examples: I know a well respected celiac who walked through a rice flour mill while they were also processing wheat flour. She had a definite celiac reaction and never finished the tour. A company that produced a snack bar that was labeled GF recieved numberous reports of celiac problems after a nearby machine was used to produce a snack bar with oats. In the snack bar situation, the danager was greater because of the number of bars eaten in a short period by several celiacs. Their primary source of food while driving for several hours.