My smoke alarm went off at 4am this morning ,, not taking any chances the first thing I did was take the garden hose and spray the whole inside of my house down and then the roof . When the fireman arrived he said there didn't seem to be a fire anywhere. When I told him about the alarm going off he said they will beep once in a while when the battery gets low. Very knowledgeable man. He said but look on the bright side , it looks like all of your houseplants got watered.