Airbag protection versus compartment intrusion effect determines the pattern of injuries in multiple trauma motor vehicle crashes.

OBJECTIVE: A prospective study of the interaction between airbag (AB) and seat-belt (Bt) protection versus vehicular compartment (VC) intrusion effects on injury patterns in motor vehicle crash (MVC) trauma patients. METHODS: Two hundred MVC patients, nonejected drivers or front seat passengers with multiple trauma or severe lower extremity (LE) trauma admitted to two Level I trauma centers. RESULTS: In frontal crashes, airbags (AB) more than Bt reduced Glasgow Coma Scale severity in brain injury, face fracture, shock, and the need for MVC extrication (all p < 0.05). Frontal AB also had a protective effect on LE fractures (41% vs. 66%, p < 0.01), but had no significant protective effect on pelvic fractures. When AB protection was present, it prevented brain and face fracture injuries caused by impact contacts and reduced the incidence of these injuries resulting from VC intrusions (p < 0.05). Thoracoabdominal injuries resulting from steering wheel intrusion showed AB protection against intrusions of twice the magnitude of those seen in non-AB vehicles (p < 0.05). In frontal MVCs, AB reduced LE fracture contact injuries but did not prevent LE fractures resulting from intrusions of instrument panel, toepan, or floor pedal structures. In lateral MVCs, Bt did not protect against brain, face, thorax, or pelvic injuries. CONCLUSIONS: Safety measures beyond frontal airbags must address frontal crash LE injuries induced by steering wheel, instrument panel, and toepan passenger compartment structure intrusions. Lateral crash injuries may profit from side AB supplemental restraint protection.

An International Marine-Atmospheric 222Rn Measurement Intercomparison in Bermuda Part I: NIST Calibration and Methodology for Standardized Sample Additions.

As part of an international 222Rn measurement intercomparison conducted at Bermuda in October 1991, NIST provided standardized sample additions of known, but undisclosed ("blind") 222Rn concentrations that could be related to U.S. national standards. The standardized sample additions were obtained with a calibrated 226Ra source and a specially-designed manifold used to obtain well-known dilution factors from simultaneous flow-rate measurements. The additions were introduced over sampling periods of several hours (typically 4 h) into a common streamline on a sampling tower used by the participating laboratories for their measurements. The standardized 222Rn activity concentrations for the intercomparison ranged from approximately 2.5 Bq · m-3 to 35 Bq · m-3 (of which the lower end of this range approached concentration levels for ambient Bermudian air) and had overall uncertainties, approximating a 3 standard deviation uncertainty interval, of about 6 % to 13 %. This paper describes the calibration and methodology for the standardized sample additions.

Preparation and Calibration of Carrier-Free 209Po Solution Standards.

Carrier-free 209Po solution standards have been prepared and calibrated. The standards, which will be disseminated by the National Institute of Standards and Technology as Standard Reference Material SRM 4326, consist of (5.1597 ±0.0024) g of a solution of polonium in nominal 2 mol · L-1 hydrochloric acid (having a solution density of (1.031±0.004) g · mL-1 at 22 °C) that is contained in 5 mL flame-sealed borosilicate glass ampoules, and are certified to contain a 209Po alpha-particle emission rate concentration of (85.42±0.29) s-1 · g-1 (corresponding to a 209Po activity concentration of (85.83 ±0.30) Bq · g-1) as of the reference time of 1200 EST 15 March 1994. The calibration was based on 4πα liquid scintillation (LS) measurements with two different LS counting systems and under wide variations in measurement and sample conditions. Confirmatory measurements by 2πα gas-flow proportional counting were also performed. The only known radionuclidic impurity, based on α- and photon-emission spectrometry, is a trace quantity of 208Po. The 208Po to 209Po impurity ratio as of the reference time was 0.00124 ±0.00020. All of the above cited uncertainty intervals correspond to a combined standard uncertainty multiplied by a coverage factor of k = 2. Although 209Po is nearly a pure α emitter with only a weak electron capture branch to 209Bi, LS measurements of the 209Po a decay are confounded by an a transition to a 2.3 keV ( Jπ= 1/2-) level in 205Pb which was previously unknown to be a delayed isomeric state.

Construction and Calibration of the NIST Large-Area-Source X-Ray Counting System.

This paper describes the construction and calibration of the NIST large area x-ray counting system. 238Pu sources 8 in (20.32 cm) by 5 in (12.70 cm) thick, emitting L x rays in the range of 12-20 keV are calibrated for total emission rate and also for rate through a centrally located 3 in (7.63 cm) diameter aperture. Alpha particle emission rates are obtained using the known x-ray to alpha particle abundances. The sources will be used to calibrate alpha-particle surface monitors.