In the days when garden centres etc sold bags of compost containing peat, I filled some garden pots with the stuff and planted my summer bedding. In the first week of June I had bunch of friends round for lunch and us smokers went out to the patio for a fag. One person stubbed his out in one of the flower pots, and we all went back indoors.
About ten minutes later a cloud of smoke passed by the patio doors, seen from inside, and when I went out to investigate the patio pot with the fag end was smouldering nicely. Water of course did nothing to extinguish it so we smothered it with gravel. Back indoors it clearly hadn't been extinguished.
It took the best part of a week to douse the impending fire by adding more and more gravel until no air whatsoever could reach the compost.
Not long afterwards, peat was banned from bags of compost!
I grew up in Glossop, just a few miles from Saddleworth Moor. It's so sad to hear of idiots playing with danger, completely unaware of the devastation it can cause.