Remove furniture and items in the room.
Seal off the entire room by hanging two millimeter plastic sheets from the crown molding all the way to the floor (Image 1).
Put a window fan in the window for added ventilation.
Add a drop cloth with a waterproof backing to the floor (Image 2).
If the popcorn was added before 1979, get it tested for asbestos by either wetting down a small area with a sponge and scraping off a little to place in a small bag, or by having a professional come out and test it.
Use a basic garden sprayer to wet down the ceiling. This will soften the ceiling texture and help to break down the adhesive bond making scraping easier.
Work in an area about 5 feet square. It’s better to make several passes than allow the popcorn ceiling to absorb too much water which could damage the paper surface and the wallboards underneath.
Once you're done, you'll need to paint your ceilings. Here are some helpful tips to make your painting easier.