Research

• Wildland Firefighter Medical Standards
• Australian Medical Examinations

Wildland Firefighter Medical Standards

All medical standards, and all medical clearance decisions, must be based on the actual requirements for safe and efficient performance of the job. The standards for wildland firefighters are no exception. The team that developed the standards interviewed firefighters, observed firefighting operations in many fire situations and in different types of terrain, and reviewed available literature on medical aspects of firefighting and safety. A summary of the primary bases for the standards may be found at http://medical.smis.doi.gov/wlffmedstdsbasis0902.pdf. A few examples of pertinent studies relating to the standards follow.

Color Vision—A tech tip by Bob Beckley, Flagging for Firefighting Escape Routes and Safety Zones (0151–2339–MTDC), reviewed the colors and styles of flagging ribbon available. The report notes that color blindness affects about 10 percent of the population. Individuals with impaired color vision were able to see lime-green flagging best. Those with normal color vision could see hot-pink flagging best. The tech tip recommended using hot pink flagging, but said that lime-green flagging could also be used on crews that have colorblind members. The medical exam includes an assessment of color vision. The standard requires normal color vision. A firefighter who can't meet this requirement needs to be identified so that proper escape flagging can be used by crews to which the firefighter is assigned.

Hearing Aids—Hearing is essential for normal verbal communication among crewmembers, including warnings, instructions, and social interaction. Firefighters need to detect natural sounds in the environment to identify movement and possible threat posed by rolling rocks or logs, and by fire itself. The ability to localize sounds accurately, particularly in low-light situations and with loud, competing background noise, was widely expressed by firefighters and managers as critical to firefighter safety.

According to the American Medical Association's Guides to the Evaluation of Permanent Impairment, hearing is considered normal if the individual can first detect noises at 25 decibels or less in the typical speech frequencies (500, 1,000, 2,000, and 3,000 hertz). The wildland firefighter medical standard for hearing was set at 40 decibels, which is considerably worse than normal, but is still within the range at which conversation can effectively occur. The ability of a firefighter to hear natural sounds, as well as heavy equipment sounds, is important for safety. Most such sounds are in the low frequency range (1 to 500 hertz).

Hearing aids are not permitted under the medical standards because of a problem with feedback in the hearing aid during the hearing test, the problem of maintenance of these high-tech devices under fire and fire-camp conditions, the risk of dislodging them in an emergency when they may be most needed, and the common problem of loss of critical and safety-sensitive directional hearing when they are being used. Studies have documented the directional hearing problem with hearing aids (Noble, W.; Byrne, D. 1990. A comparison of different binaural hearing aid systems for sound localization in the horizontal and vertical planes. British Journal of Audiology. 25(4): 285. Kimberly B.P.; Dymond R.; Gamer, A. 1994. Bilateral digital hearing aids for binaural hearing. Ear, Nose, and Throat Journal. 73(3): 176–179. A waiver may be considered for individual firefighters who require hearing aids to meet the hearing standard if they can demonstrate that their directional hearing is not significantly impaired, as several studies indicate may be possible (Byrne, D.; Noble, W.; Glauerdt, B. 1996. Effects of earmold type on ability to locate sounds when wearing hearing aids. Ear Hear. 17(3): 218-228. Kojbler, S.; Rosenhall, U.; Hansson, H. 2001. Bilateral hearing aids—effects and consequences from a user perspective. Scandanavian Audiology. 30(4): 223–235).

Needed Research

Visual Acuity and Depth Perception—Several factors are involved in normal depth perception by humans, including such things as overlay, shadows, texture density, known size, and stereopsis, or binocular vision. Binocular vision depends upon visual acuity in both eyes, which is why both eyes are tested and recorded separately in the medical standards exam. When visual acuity is impaired, due to loss of an eye or inadequate correction with lenses, such as contacts or glasses, stereopsis also is impaired, which may interfere with good depth perception. Depth perception also is tested directly, using a vision testing device in the clinic (during the baseline and periodic exams, but not during the more limited annual medical screenings). It is not clear just how limited a person's depth perception can be and still provide for a margin of safety, particularly in low-light situations, or on steep slopes, when a firefighter must move quickly. The medical standards team would like to see research conducted on visual acuity and depth perception, to determine more precisely the standards that should be applied, particularly to new hires who may not have the experience and field judgment of a seasoned firefighter.

Causes of Injury, Illness, and Death—Glenn Fischer, the Northeast Oregon area inventory coordinator, prepared a summary in December 2002 of the almost 30,000 fire camp medical unit visits recorded during 2002. The data provide critical information that can assist planners making staffing and supply decisions. Most visits are for minor, acute illnesses that are predictable and difficult to prevent in a crowded fire camp. Measures to assure that firefighters have adequate rest, nutrition, fluid intake, and hygiene have been addressed in previous issues of Wildland Firefighter Health and Safety Reports, and will continue to be emphasized because of their importance to firefighter health. Many of the visits, however, involve injuries or more serious illnesses. It is not known how many of these visits relate to medical conditions that might be prevented by enhanced preassignment medical evaluations.

On-the-job fatalities among wildland firefighting were summarized in the 1999 report, Wildland Fire Fatalities in the United States: 1990 to 1998 (9951–2808–MTDC) by Richard Mangan, through the Forest Service's Technology and Development Program. During the study period, 133 deaths were associated with 94 separate events. Causes cited for these deaths included burnovers (29 percent), aircraft accidents (23 percent), heart attacks (21 percent), vehicle accidents (19 percent), and falling snags (4 percent). Four percent of deaths were due to other causes. What is not clear from available data is the role that a firefighter's medical status might have played in these deaths.

To what extent was impaired vision or hearing a factor in the accidents that occurred? Could any of the heart attacks have been prevented by better screening? Did nutritional or immunological stresses reduce the ability of some firefighters to recognize dangerous situations, and to take steps to avoid them? Better data on the medical status of firefighters, which the medical standards program will provide, and more complete reporting of contributory factors when serious illnesses, injuries, or deaths occur, may help improve the health and safety of firefighters.

Kevin Jensen is the manager of the Interagency Medical Standards Program. Jay Paulsen, M.D., of the U.S. Public Health Service's Federal Occupational Health Program is the program's medical advisor.

Australian Medical Examinations

The Division of Natural Resources and Environment, Victoria, Australia, requires firefighters to take a medical examination before seasonal employment as a bush firefighter. The examination is a comprehensive look at health issues directly related to firefighting within the bush environment. All project firefighters must successfully complete the medical examination and a task-based (job-related work capacity) assessment before being offered employment within the organization. The medical assessments are conducted by doctors who receive special training in the conduct of the firefighter examination. Services are provided by local physicians and by mobile physicians.

In the 1996-1997 fire season, 7 percent of 395 applicants failed the medical examination, and in 1997-1998, 3 percent of 832 applicants failed the exam. The major health categories associated with exam failure in 1997-1998 were: vision (22 percent); respiratory (18 percent); cardiovascular (9 percent); ear, nose, throat (6 percent); musculoskeletal (6 percent); and endocrine (6 percent). The failure rate for vision was a decrease over the previous year. However, even though the vision standard had been relaxed, vision was still the major factor in failure.

In the 1996-1997 fire season, the task-based assessment, included the pack test and a timed circuit with a bag carry and hose drag. The circuit was dropped in 1997-1998 and replaced with the requirement that the applicant be able to carry the 45-pound pack used for the pack test. Pass rates on the pack test were 97 percent in 1996-1997 and 96 percent in the 1996-1997 fire season.

Ellis, S. 1998. Evaluation of Medical and Taskbased Assessment. Natural Resources and Environment, Victoria, AU. Sue.Ellis@nre.vic.gov.au