Yes, might be useful if a fire happened to start on the floor or the plants start burning. I presume the most risks for fire are electrical fires, with lights and fans the prime suspects. But bags dropping fire extinguisher powder will likely not doing anything for these fires. Otherwise, how/what will release suspended powder before it's too late? If the bag has to melt to release the powder, there is likely already flames and the fire is spreading.Speaking of fire proofing a grow room, I had an ideal about plastic bags full of the powder in a extinguishers. Then if a fire ever happened you would only lose the crop.