Any time I have used Vermiculite, pearlite, peat moss from a bale or any other Dusty amendment I wear a Respirator (that has canisters on the sides), Dust masks are far to leaky around the edges and they don't filter out the particle sizes that are most harmful to your lungs.
Norton and some other companies make not so expensive models and some of these are available at most hardware stores or lumber companies, even Harbor Freight carries some that will be fine for our uses in
gardening.
Eye protection is also advised when using dusty amendments since fine particles like to enter our bodies through them.
Vermiculite is a good amendment since it will hold
water well over a longer period of time and it helps keep the soil open for air and water infiltration.
Redhawk