Protect yourself from possible asbestos exposure by using a face mask, eye goggles and latex gloves.
Add a few drops of liquid dish detergent to a water bottle and fill it with water, shaking gently to combine ingredients.
Spray the ceiling in various areas around the room to get an accurate sample. Wet the areas thoroughly.
Scrape a 1-square-inch section of the wet popcorn using a putty knife. Scrape the popcorn sample into a zip-lock plastic baggie and seal. Repeat the procedure at the other sprayed locations on the ceiling.
Send your results to an asbestos consulting and testing center to confirm whether your ceiling contains asbestos. Find a laboratory by contacting The National Institute for Standards and Technology or your local health department, or use the yellow pages. There is usually a fee for testing asbestos samples.
Wait for results. Even if the results are negative, take two more ceiling samples from different locations in the room to confirm the results. This will allow you to be sure there is no asbestos anywhere in the popcorn.