The smoke could be extremely toxic and no one should have been down wind unless they were wearing a 3M sealed mask with a suitable filter. As a welder anytime we are welding in a space that doesn't have open air and a breeze we are strongly advised to wear a mask. The metal vapors off welding can cause severe and long lasting physical degradation. I've experienced it myself before masks became common place. Fortunately I only got metal fever twice and that was enough to take it seriously. One of my coworkers exposed to paint fumes while welding went down and started having convulsions.