Dust Walls
This is an extremely dangerous, and common, occurrence in low areas all around the world. Dust walls are typically generated by a mixture between long-term droughts and rapid shifts of temperatures between the ground and atmosphere. When the ground is hotter than the air, or vice versa, a high-pressure system can develop and sweep up massive amounts of dirt and dust. That high-pressure system will migrate, just like a thunderstorm does, and pass over populated areas because the ground temperature is naturally warmer than in non-inhabited places. If you find yourself in a dust storm, cover your face and eyes and try to get inside anywhere you possibly can.