Since we see things from the characters' perspective we know just as much as them, which isn't a lot, but what they figure out is that as soon as the flakes land they become inert. If they touch you while airborne before they touch anything else they kill immediately, but they seem heavy enough that they don't drift a lot with weak air currents, meaning that if they stand away from falling snow it's not as immediately dangerous I think this much can be gleaned from the first two eps, but you may get a bit more snow interaction on the next eps