Fun little tangent; I don't know how old my smoke detectors are, but the one by my front door gets a little test every now and again. One of my neighbors burns

Fun little tangent; I don't know how old my smoke detectors are, but the one by my front door gets a little test every now and again. One of my neighbors burns a fireplace on cold days. Invisible (but smellable) quantities of wood smoke pool under the rafters of my porch; the next morning, when I leave through the door, the smoke alarm always chirps for a moment! It amazed me how sensitive it is, when I first figured out what was going on.