This is a thread worth responding to. I am a university professor of cardiology and can tell you that cornstarch is an interesting study. We call it a "bear suit" substance. It is of a family of airbornes that when inhaled over a modest period of time will cause permanent conditioning of the lung tissue to form an inner shell of rather inflexible sheathing. In extreme cases it can cause the feeling of being in a bear hug or tight suit. It will not go away. As if that is not enough of a problem, over time this will put pressure on your cardiovascular system leading to increased risk of stroke and heart disease. Baby powder (not the talc kind) and many other household products are in this family. Research shows that it is possible to suffer permanent damage in just a few days of 30 seconds exposure. Granted that is rare (about 500 cases a year) the danger increases as the exposure does. I would never volunteer to run for 40 minutes in these conditions.
President Ford, Willie Mays are two high profiles who suffered for years with this. It is surprising to me that this danger is not better publicized. Take a good look at warning labels that are on the home medics. The warning is starting to show up more there but because of the rarity there is no federal requirement yet. It's coming though. I promise. I'd like to see this repeated on the same stuff in your kitchen.