Add just enough water to 5 cups of baking soda to make a thick paste. The paste should be the same consistency as toothpaste and should be spreadable. Baking soda is a natural cleaning solution that will absorb odors.
Spread the paste over the marble fireplace’s vertical surfaces. Let it sit for several hours until it dries completely.
Sprinkle baking soda over the horizontal surfaces and let it sit several hours.
Wet a soft-bristled scrubbing brush with water and scrub it over the entire fireplace surface. Wet the brush again as soon as it dries out. Scrub until the surface is covered in wet baking soda paste.
Let the baking soda sit several hours until it dries completely. As it dries it will pull the cigarette smell from the marble.
Sweep the baking soda into a trashcan.
Repeat the process until the smell is gone.