It can take a few days for construction dust to settle, but it depends on the type of surface that it's settling on. If it's a smooth surface, then it will take longer for the dust to settle because there is less friction to help it move down. If it's a rougher surface, then the dust will settle more quickly because there is more friction to help it move down.

It takes about a week for construction dust to settle. Dust particles are generally round and have a Mohs hardness of about 3.5, which means that they are scratched by a copper penny. They range in size from about 0.001 to 100 micrometers in diameter. A human hair is about 70 micrometers in diameter, so a dust particle is much smaller than a human hair. Larger particles will settle faster than smaller particles because they have more inertia and are more likely to collide with other objects in the air, causing them to fall out of the air more quickly. Lighter particles will also settle faster than heavier particles because they have more buoyancy and will be carried by air currents for longer distances