Party poppers are not permitted onto an aircraft under any circumstances. Leave them at home.
Party poppers contain a form of explosives that creates the pop sound and ejects the streamers / confetti. If taken in quantities would present as a significant risk to passengers, crew and the plane.
You will be asked to relinquish all dangerous or prohibited items found in your carry-on luggage. If you refuse:
We x-ray bags going on planes to make sure there is nothing dangerous in them. If something comes up on the x-ray that needs checking, the bag will be opened, searched and any dangerous or prohibited item will be removed.