Smoke and carbon-monoxide alarms

Being safe is harder than it should be

Here's a challenge to America's smoke and carbon-monoxide alarm industry: Create one device that can sense flames and smoke and warn you about carbon monoxide. Our tests of 25 alarms show that safety is far too complicated.

For example, smoke alarms that use ionization technology were great at detecting a fast-flaming fire, like burning paper, but lousy at warning you of a smoldering fire, say, in a mattress. The opposite was true of photoelectric versions. A few smoke alarms, which use both technologies, warn you of both types of fire, but they don't detect leaks of CO, a colorless, odorless gas emitted by fuel-burning appliances that can cause brain damage or death. And combined smoke and CO alarms detect only one type of fire, depending on the maker.

Getting all of a home's alarms to communicate with one another via an electrical line or wireless signal, so you would be warned about a fire or CO leak in the basement even if you were asleep upstairs, is another hurdle. Adapters enable hardwired alarms to be connected with those made by a competitor. But wireless alarms can communicate only with other wireless alarms from the same company, since manufacturers use different frequencies. The industry should fix this problem.

Fortunately, you can safeguard your household with some mixing and matching. What's more, several models provide excellent protection (for subscribers). And any of the tested units would be better than having no detectors at all.