Health hazard evaluation report: HETA 2002-0354-2931, Horizon Air, Seattle, Washington.
A request for a health hazard evaluation (HHE) from flight attendants at Horizon Air in Seattle, Washington, was received by the National Institute for Occupational Safety and Health (NIOSH) on September 23, 2002. The flight attendants were concerned that their long work shifts may result in overexposure to noise from the airplanes to which they were assigned. Particular concern was noted about Horizon Air's fleet of turboprop aircraft when the noise and vibration suppression (NVS) system was inoperable. An initial site visit was made to Horizon Air in Portland, Oregon on November 12, 2002, to meet with a management official and the local flight attendant's union president to describe the survey. Once approval to operate noise measuring equipment aboard aircraft was obtained, a survey of the three types of aircraft used by Horizon Air, the Bombardier Q200 and Q400 turboprop and CRJ regional jet, was conducted from May 19-22, 2003. Two examples of each aircraft type were chosen by the company, and the NIOSH investigator traveled on several scheduled flights to capture noise levels in the front, middle, and rear of the passenger cabin. One-third octave band spectra were integrated for 15-second periods and stored in the noise analyzer for later analysis. Five minutes of the noise exposures encountered during take-off, landing, and at cruising altitude were stored for each aircraft. This measurement protocol allowed for the reporting of one-third octave band noise spectra for the various riding locations along with overall A-weighted and unweighted noise levels. An estimate of the flight attendants' noise dose was calculated from the spectral measurements collected on each flight. Noise measurements showed that the levels encountered on individual flights were not enough to increase an employee's or the public's risk for hearing loss, and therefore, no health hazard was identified. Even when the noise exposures from the multiple flights taken by the flight attendants during a day's schedule were combined, the attendants would need to take 12-24 of these flights per day before realizing an increased risk of occupational hearing loss. The noise results along with data published by Bombardier do show that the NVS system needs to be operating according to specifications to keep the noise levels below evaluation criteria. Recommendations about hearing protection and the NVS system are offered in this report.