I foolishly blew up a significant amount of concrete sawdust and this was inhaled by my children and I. Are we at risk for silicosis or anything else? My youngest son even sneezed from it.

Unlikely. Although this is not a great exposure to get, the lungs do have a system that will remove the dust over time. Those who get silicosis are generally chronically exposed to the dust in their working environment without using protective gear.