Put on the safety goggles, gloves and the breathing mask. Doing so will prevent you from inhaling plaster dust, which has harmful effects on health.
Pick up pieces of plaster and place them in the heavy duty trash bag. Make sure that the trash bag does not become too heavy, since this will rupture the bag and create an even greater mess.
Sweep smaller pieces of plaster as well as dust into the dustpan, being very careful to avoid stirring the dust. Do this task gently in order to prevent the dust from spreading.
Vacuum the room using a wet/dry combination vacuum. The wet vacuum setting will help clean up any lingering plaster dust particles without spreading the dust. Allow the floors to dry and then vacuum using the dry setting to ensure thorough removal. Use the attachments in hard to reach places of the room, including corners.
Fill a bucket with warm water. Dip the rag in the bucket and wring it out. Wipe the rag along surfaces in the room such as walls, windows and any furniture that may have become dusty.