Last month, 40-year-old international tennis star Vitas Gerulaitis died in the guest cottage of a friend's Long Island estate. Cause of death: carbon monoxide poisoning from a faulty propane heater.
Carbon monoxide is the number-one cause of death by poisoning in the United States. About 1,500 people die each year from accidental exposure to high indoor concentrations of the gas. In addition, tens of thousands of people are exposed to non-fatal levels, resulting in headaches, nausea, fatigue, dizziness, aggravation of heart conditions, and brain damage.
Although carbon monoxide is a known killer, there has been no practical method for monitoring levels of the gas. There are some consumer warning devices on the market, but they do not provide detailed information about concentrations.
"There is no good method for measuring CO in residences or in the workplace," says LBL physicist Greg Traynor. "You have to use expensive real-time instruments that need on-site calibration to measure concentrations. It's expensive and awkward."
Traynor, a member of the Indoor Environment Group of the Energy and Environment Division, has been working with E&E's Mike Apte and Gee-Minn Chang to develop an effective, inexpensive, passive CO monitor.
Working with The Quantum Group, Inc., a small San Diego firm, Traynor and Apte designed a device that samples room air for a week. The passive sampler's sensor is a small disk about a centimeter in diameter. The disk sits inside an air diffusion tube contained in a glass vial filled with a silica gel to keep the CO-sensing mechanism dry. Another tube lets air into the vial. As the disk is exposed to CO, the amount of near-infrared radiation getting through it decreases and the disk turns darker. The disk can then be put in a spectrometer to determine CO concentration.
Carbon monoxide is a product of incomplete combustion. The main ways that CO gets indoors are from operating a motor vehicle in an attached garage, burning charcoal indoors, and from the use or misuse of malfunctioning or misinstalled combustion appliances that run on fuels such as gas, kerosene, propane, or wood.
Malfunctioning combustion space heaters, like the one that killed Gerulaitis, inject CO into houses via cracked heat exchangers or blocked or missing flues. CO can also be a serious problem if an unvented gas stove is used to heat a house.
The Department of Energy is concerned about CO levels indoors, because its weatherization programs to save energy can tighten houses and other buildings enough to increase CO concentrations. To test the residential sampler, Traynor plans to do a field survey to identify U.S. houses likely to have high CO levels. He and his co-workers will then mail monitors to those households to identify houses that need mitigation. Each household will be asked to mail the disk back to LBL, where a spectrometer will be used to determine CO concentration in the house.
The residential passive monitor may eventually serve as a screening tool for utility companies.
"They usually send technicians only at hook-up time or when there is a customer service problem," Traynor says. "We'd like to see them get more active."
Now LBL has signed a three-year, $600,000 Cooperative Research and Development Agreement (CRADA) with The Quantum Group to develop an occupational dosimeter for carbon monoxide. It will probably be worn on a worker's lapel to measure exposures for eight-hour work days and ensure compliance with OSHA standards. Traynor expects that the dosimeter will use inexpensive technologies similar to the residential monitor.