Background Whereas most of the initial FMVSS 214 vehicles used padding and/or upgraded structure to protect occupants from thoracic or abdominal injury in side impacts, by MY 2001, 22 percent of new passenger vehicles had special air bags designed to provide an additional cushion between the occupant and the side structure. By MY 2003, many vehicles were also equipped with head air bags to enhance protection against head injuries, as required by FMVSS 201, and to help prevent occupant ejection through side windows. Available technologies include: (1) Door-mounted side air bags; (2) Seat-mounted side air bags; (3) Seat-mounted, integral torso + head air bags; (4) Roof-rail-mounted, tubular head air bags; and (5) Roof-rail-mounted head "curtain" air bags. Side air bags and head air bags are not mandatory, but NHTSA regards them with favor and provides consumer information on their availability, by make-model, in Buying a Safer Car.

Objectives Estimate the effect of side air bags on fatality and injury risk in side impacts. Study the effect of head-impact air bags on fatality rates, head-injury rates, and occupant ejection rates. Compare the effectiveness of the various types of side air bags and head air bags. Estimate the cost of head air bags. Compare the Thoracic Trauma Indices [TTI(d)] and other measures of test performance of vehicles with side air bags/head air bags to similar vehicles without the air bags.

Proposed Approach FARS (including the enhanced FARS file with cause-of-death information) and NASS data will be analyzed by methods developed in earlier evaluations of frontal air bags and side impact standards to determine the effect of side air bags and head air bags on fatality and serious-injury risk, as well as the effect of head air bags on occupant ejection. Databases of test performance, for vehicles with and without side air bags/head air bags will be assembled from FMVSS 214/FMVSS 201 compliance tests and Side NCAP tests. The cost of these air bags will be estimated from "teardown" analyses. The evaluation may require 2-3 years or more until sufficient FARS data accumulate for a definitive, final report; the agency may possibly also issue an interim report.