NEWS OF THE W EEK
REPORT HITS SAFETY BOARD REVIEW: Auditors want agency to investigate far more industrial accidents
T
HE CHEMICAL SAFETY & Hazard Investigation Board (CSB) should quintuple its chemical accident investigations, Government Accountability Office auditors say in a new report. GAO notes that the board—an independent agency charged with investigating industrial chemical accidents—last year identified some 31 fatal accidents warranting a full investigation but examined only six of them. CSB Chairman John S. Bresland, in a letter to GAO, notes that the board agrees with “various points in the report” but has concerns with many of GAO’s other “conclusions and characterizations.” To identify the 31 accidents, CSB considered some 900 incidents, which it discovered from federal data and media reports. The accounting office wants CSB to change its reporting system and develop a regulation requiring firms to CSB
The 2007 Valero McKee refinery explosion in Sunray, Texas, is the most recent of 47 investigations completed by CSB since 1998.
O2 REQUIREMENT FOR BURNING RISES ATMOSPHERIC CHEMISTRY: Experiments
suggest Mesozoic oxygen levels were higher than previously expected
S
OPHISTICATED NEW combustion experi-
ments put some of the strictest lower limits yet on atmospheric oxygen levels needed to allow burning. University College Dublin researchers Claire M. Belcher and Jennifer C. McElwain report the lower limit for atmospheric O2 that will support combustion is higher than previously predicted (Science 2008, 321, 1197). This finding has implications for the atmospheric composition of the Mesozoic Era, 251 million to 65 million years ago, during which several mass extinction events occurred that could have been caused by low oxygen levels. Because many fire records date back to this period, scientists have proposed that the atmosphere at that time had enough O2 to support combustion. Earlier combustion experiments suggested a lower limit of 12%. The new work finds a lower limit of 15%, indicating that the Mesozoic atmosphere contained more O2 © 2008 SCIENCE
Belcher tests the combustion of materials in a chamber that varies atmospheric O2.
WWW.C E N- ONLI NE .ORG
12
formally report chemical accidents directly to the board. Another GAO recommendation would give the Environmental Protection Agency’s inspector general authority to permanently oversee CSB management. These recommendations were primarily based on GAO’s reading of an amendment to the Clean Air Act of 1990, which created the board. CSB does not agree. It does not believe the law requires it to investigate all serious accidents, Bresland notes. But in his letter he acknowledges that CSB’s mission—helping avoid chemical accidents—would be strengthened by more investigations. Hence, CSB will seek a bump up in congressional funding to allow it to investigate more accidents. The CSB budget has been flat throughout its existence. The board also says that within three months it will solicit public comments on the need for an industrywide, formal accident-reporting regulation. GAO’s oversight of CSB stretches back to 2000, when the board faced difficult management problems. Bresland says in his letter that these difficulties have been overcome. The board was particularly concerned that several GAO recommendations called for oversight by EPA. CSB notes that it has criticized the regulatory agency in its accident reports, and consequently, EPA oversight may limit CSB’s independence.—JEFF JOHNSON
than previously thought. Today’s atmospheric O2 hovers around 21%. “This is the first experiment to really go after the lower O2 limit; other experiments were more interested in general behavior and the upper limit,” notes Richard Wildman, a graduate student at Caltech who recently performed burning experiments in the lab of Robert A. Berner, a geology and geophysics professor at Yale University. Berner has developed pioneering models of Mesozoic atmospheres. Combustion experiments are difficult, and Belcher’s lab, with its controlled atmosphere, took three years to set up and cost more than $1.4 million. Belcher says the lab, in which they burned sphagnum moss, matches, wood, and paper, contains some unique features, such as a nitrogen generation plant to displace O2. “This combination of gas control and gas-level accuracy has not been achieved before,” she says. Belcher and McElwain also included a thermal-imaging camera, a tool not previously used in such experiments, to precisely determine the onset of combustion. “Wood and plant material will char at all ranges of O2, and therefore, charring itself is not a measure of combustion,” Belcher says. Berner notes that his models suggest that very dry wood might still have burned at O2 levels lower than 15%. “Our result—burning of wood at 2% moisture and 12% O2—is not unreasonable for bone-dry dead ground cover, which often acts to initiate a larger scale fire,” he says.—ELIZABETH WILSON
S E PTE M BE R 1 , 20 0 8
