Sensors: Where there's smoke there'd better be a smoke detector. Inexpensive, life-saving systems vie for consumer interest

Each year in the U.S., fires kill more than 12 000 people, injure another 300 000-50 000 of them seriously enough to need hospitalization, and cause about $3 billion in property damage. Most of these fatal fires occur at night and, characteristically, produce smoke and fumes that are even more dangerous than heat and flames since they may not be detected until sleeping occupants of the building are overcome.