The dust can kill a person if he's exposed to it for even a small period of time. Many survivors that are unfortunate to get stuck in the dust are either affected by it like Victim 18, or die shortly after exposure.
A gas mask can protect anyone against the dust so it's possible to stay on the ground longer. Even though the dust is dangerous, the ground area holds many consumables and items needed by the protagonist and victims. The covered area should still be scoured strategically due to this.
- Despite the dangers of the dust, some survivors encountered inhabit the dust-filled environments without masks on.