In the interest of public safety, I’m going to skip to the punchline: check your smoke detectors. Not later, not after dinner or the game, but right now.

Poke the button with a broomstick; endure the ear-splitting alarm; change the batteries, if necessary; or replace the thing entirely if it has exceeded its rated life.

This is the season of firing up the boiler against the chilly night air, or pulling the ceremonial first log off the pile for the wood stove. There’s no excuse for postponing a potentially life-saving battery check, especially when you consider that something like two-thirds of the fatalities from domestic fires occur where there’s no operable smoke detector in the home.

It’s not very sexy, but that six inch disc of white plastic is a technological marvel, one that has been 120 years in the making.

Believe it or not, the first battery-powered fire alarm was patented in 1890 by Francis R. Upton, an early pioneer in electrical engineering. Mr. Upton’s “Portable Electric Fire Alarm,” which he invented with his partner Fernando Dibble, had many of the features of today’s detectors: a dry cell for powering the device; a thermocouple for detecting heat; a make/break circuit that closed when the ambient temperature exceeded a predetermined level; and a battery-powered bell to sounded the alarm.

Unfortunately, the device was quite large and prohibitively expensive, the kind of thing you might buy for your warehouse or factory, but not for your home. Its success in detecting fires was based on sensitivity to heat, which was certainly a step in the right direction, but, as a century of data would show, was much less effective for saving lives than the detection of smoke.

The science of smoke detection would take another forty years to develop. Like many of the great discoveries, it was based on an accident. On the eve of World War II, a Swiss physicist named Walter Jaeger was working on a device that would detect invisible poison gas. Frustrated by the failure of his latest prototype, a detector that used ionized air as a kind of electronic sniffer, Mr. Jaeger lit a cigarette to clear his head. He noticed that the cigarette smoke caused precisely the drop in voltage in his ionizer that he’d been looking for, and the ionization smoke detector was born.

But the technology didn’t ripen until the 1960s, when advances in computer chips and nuclear technology made it possible to manufacture inexpensive smoke detectors on a massive scale. Solid state electronics and disposable batteries solved the problems of miniaturization and inexpensive power; and a ready supply of the radioactive isotope Americium-241 made it possible to have a tiny ionization chamber that could last indefinitely.

That’s right: every smoke detector that uses ionization has a bit of radioactive material inside. Not to worry, though. We’re talking about such a minuscule bit of the isotope that you’d practically have to swallow a smoke detector to come to any harm. At which point, a speck of Americium would be the least of your problems.

Ionization smoke detectors are supremely sensitive when it comes to detecting fires that are mature and growing. But they’re not as good at sniffing out a smoldering fire that hasn’t yet burst into flames. For that, your better bet is an “optical” or “photoelectic” detector, which uses photoelectric cells to detect large smoke particles, the kind most often emitted by smoldering fires. Optical detectors are much less likely to be triggered by kitchen smoke or steam from a shower, which is significant because repeated false alarms will often drive a homeowner to disable an otherwise perfectly healthy smoke detector.

For the record: according to a recent report by the National Volunteer Fire Council, in rural Pennsylvania, 37% of homes have at least one smoke alarm that doesn’t work.

So check your smoke detectors!

The National Fire Protection Agency recommends that you have both kinds of smoke detectors — ionization and optical — in your home. This can be as easy as buying one of the combination detectors on the market, or, if you want to cut down on false alarms, by installing the optical type near your kitchen to balance out the ionization detectors that are probably already in your bedrooms.

Nowadays you can even buy an inexpensive detector that combines smoke detection with carbon monoxide detection, for the best of both worlds.

Just keep in mind that even the fanciest, newfangled, talking, CO-sniffing, photoelectric/ionization device with smart hush and built-in escape light — phew! — is worthless without good batteries.

So do yourself and your family a favor: check your smoke detectors.

This column was published in the Perry Co Times on 18 October 2012

For more information, please contact Mr. Olshan at writing@matthewolshan.com