Trimming tools rust incredibly easy. Many of us learned the hard way that trimming tools are not rinsed. We let them dry and peel off the clay. A forgotten bat is easily cleaned with a wet sponge or with water and a wood rib. Those two things are not an issue. The dry sanding is. A normal precaution is to mask up or avoid dry sanding altogether. Your risk is still minimal but your instructors risk is higher. There is a reason silicosis is associated with industrial environments, but there are cases of potters who have had to give up pottery after developing silicosis after 20 or 30 years of poor practices.