(One of a series of notes detailing results of recent visits to
Lawrence Berkeley National Labs-LBNL)
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CO Sensor – Occupational Dosimeter

A new lightweight, inexpensive, accurate carbon monoxide (CO) sensor and monitoring system has been developed by scientists LBNL and Quantum Group Incorporated (QGI, San Diego), under a cooperative R&D agreement (CRADA).

The original impetus was to create a device to do population exposure studies, since outdoor measurements of levels of CO (as required by the Clean Air Act) don’t relate to deaths and acute poisonings caused by CO. CO poisoning deaths (500-1000 per year) occur indoors, involving accidents, misuse of heaters, unvented gas flames, and auto exhaust. 19,000 poisonings were reported by poison control centers in 1995.

There is limited understanding about carbon monoxide exposure risks, partly because there has been no affordable way to accurately measure CO in the field. Some of the current methods of measurement require expensive, heavy equipment or unwieldy air bag samplers. Others are relatively inexpensive and lightweight, but they are not accurate or sensitive enough to provide credible quantitative results for a large number of sites.

To fill this gap, LBNL and QGI developed the new CO sensor, which can clip onto a person’s clothing. It can be used as an occupational dosimeter, which measures a worker’s average exposure, or as a residential passive sampler measuring exposure in a home or office over a one-day to one-week period. Analysis is simple—the device is placed into a standard lab spectrophotometer which, by measuring its color change, instantly indicates how much carbon monoxide the sensor absorbed. A single sensor can be reused many times.

To test the sensor’s performance, a study was done of the CO exposure of workers at San Francisco’s Moscone Convention Center, where propane powered forklifts are active throughout, and trucks drive up to interior loading docks. (The Center already had installed a number of measures to reduce CO exposure.) Workers wore sensors and commercially available diffusion tube devices. CO levels were also measured by traditional means.

The tests showed that the device measured average workshift CO exposures accurately to within one part per million. The commercially available diffusion tube under-reported CO exposures by an average of about 3 parts per million.

QGI is now looking for private-sector partners for distribution and is developing plans to manufacture and market the CO occupational dosimeter.

See press release May 17, 1999, at:
http://www.lbl.gov/Science-Articles/Archive/carbon-monoxide-sensor.html

Contact: Michael Apte, MGApte@lbl.gov, 510-486-4699

Quantum Group (San Diego CA) produces a line of CO detection products including detectors for residential and RV use, appliance safety shut-off, and ventilation controls.
http://www.qginc.com/

Mark Goldstein, President, 619-457-3048 x103 fax 619-457-3229
Michelle Oum, Director, Sensor R&D, x110