Created several kilometers up, dangerous concentrations of this material would be driven by upper atmospheric winds, potentially leading to hazardous levels of fallout in areas up to tens of kilometers downwind.

几公里长度的，这种浓度的危险物质会随着大气层风的驱动，沉降物会顺风漂移，给几十公里以上的区域带来潜在的危险。