Never found any aspen shavings or shredded to be dusty at all. Only hear about it second hand. "ecoearth" is far dustier when dry in my experience but still didn't cause respiratory problems for milk snakes I kept on it. . And it doesn't much matter what substrate it is, I just don't let them swallow it. Accidents do happen though and I've sen them swallow small pieces which pass just fine. Probably best if he feeds in separate container with no substrate. I feed right in the tanks but only because I have a lot of experience and know how to tong feed in a way that they don't usually get substrate on the food.