Thank you for the warning, but they were bought from a specialist pest control company. The phrase 'smoke bomb' is a bit fanciful, there is no propellant or explosive effect, they just smoulder slowly and produce quite a lot of smoke. The usage instructions contain suitable warnings and give instructions on any precautions required when using them. I used these in my loft space, one of the certified and expected uses of the product. I followed the instructions and placed them in a metal tray and was able to close the loft 'hatch' thus sealing in the flies and the smoke, which I left for 3 hours before taking a peek to check on results. The smoke clears quite quickly and there is no residual effect from the insecticide - just a lot of dead flies.Always check for noninflammable propellant when purchasing these, otherwise, you may be filling the space with propane plus insecticide. Do a websearch on the possible undesirable results.