The Boston Fire Department is blaming "careless disposal of smoking materials" on decks for a six-alarm fire on Bunker Hill Street in Charlestown on July 21, a five-alarm fire the next day on Chelsea Street in East Boston and a four-alarm fire on Sawyer Avenue in Dorchester on July 26.

BFD says it's past time for smokers to stop burning buildings down:

All started outside on decks. No civilian injuries. Total apts/condos involved:23, displaced 54, dollar loss $10,000,000.+ We continue to stress MAKE SURE you COMPLETELY extinguish your cigarette, cigar or whatever else you smoke. Finally, planters are not ashtrays. And make sure you having working smoke and carbon monoxide detectors wherever you live.

A BFD spokesman adds that investigators believe the Charlestown fire was started by a hand-rolled cigarette dropped in a planter, that the East Boston fire was started by a smoker on the third floor who dropped a cigarette that landed on the first-floor deck and the Dorchester fire involved an imported cigarette on the first-floor deck. Investigators were unable to tell if that fire started in a planter or on the floor of the deck.