If you search for 'how much exposure to asbestos is dangerous' or similar, you will find that a one-time exposure is not considered dangerous. Of course it is best to avoid the dust, and every effort should be made within reason to avoid any exposure. I can attest to having been exposed to brake shoe dust a few times when shoes were arced to match the drum diameter, and also shipboard working on a WWII DD boiler service and when asbestos lagging was being removed and have wondered if/when I would become ill. I figure by now, 50-60 years on, it's not gonna happen. FWIW.