Correct temperature readings are critical to many industrial processes, and commercial applications such as storage facilities for blood or vaccines.

“Give them credit for level of work,” Strouse said. “There’s many culture behind their measurements and many cash attached. They need to be certain the replacements work to the level they need them to.”

NIST has begun working with the American Petroleum Institute and the American Society for Testing and Materials (an international body that develops consensus technical standards for industry) to identify thermometer technologies that can replace mercury.

The declining demand from business and industry for calibration of mercury thermometers at NIST labs tells the story best.

“Back in the early 1900s, they employed five people to do nothing over calibrate mercury thermometers,” Strouse said. “When I started here 20-some years ago, there was one person in the lab calibrating close to a thousand of them a year. Last year they calibrated five.”

And there’s been none in 2011. Nor is there any clamor from thermometer manufacturers to save the devices from oblivion.

Only one U.S. manufacturer of mercury thermometers Miller & Weber, in Queens, N.Y.remains in business. It, , is working “extremely hard” to phase out the expertise and sell customers more advanced products, Strouse said.

For most Americans, however, the nearest mercury is probably in their home thermostats. Millions still have the iconic, round “T87F” Honeywell thermostats, or others like it, on their walls.

Thermometers aren’t the only concern. Mercury is present in a variety of measuring devices, including some barometers, strain gauges, flow meters, blood-pressure cuffs, and in some electric switches, such as the ones that turn on car trunk lights when lids are lifted.

?