PSYCHOLOGICAL RESPONSES TO WORKING IN BUNKER GEAR
BY STEVEN J. PETRUZZELLO, Ph.D.; DENISE L. SMITH, Ph.D.;
DAVID F. CLARK, F.F., M.Ed.; and BRADLEY G. BONE, F.F., R.N.
We reported in Fire Engineering (November 1994) some of the results of a study in which we examined firefighters` physiological responses while working in different types of gear–what we referred to as “station blues,” the “hip-boot” configuration, and the “NFPA 1500” configuration. We compared heart rate, oxygen consumption, deep body temperature, and mean skin temperature and found that these findings tell only part of the story.
We also sought to determine what, if any, psychological effects the combination of physical work and bunker gear had on firefighters. To date, we have found very little research that has examined perceptual and self-reported variables beyond the perceptions of exertion. We reasoned that increased physiological stress caused by the increased heat production and heat retention of the bunker gear may result in increased psychological stress. This mental stress could be manifested in an increased sense of effort, increased anxiety, or increased negative emotions, as well as in poor (or impaired) decision making.
The description of psychological variables may provide valuable information about firefighting activities. The U.S. Fire Administration recognized the importance of psychological status when it recommended the establishment of an emergency incident rehabilitation center “to ensure that the physical and mental conditions of members operating at the scene of an emergency or a training exercise do not deteriorate to a point that affects the safety of each member or jeopardizes the safety and integrity of the response.” (USFA, 1992)
There is also a good scientific basis for expecting that psychological responses might be affected in firefighting situations. For example, the hypothalamus, a small area in the brain, is involved with temperature regulation and emotion, among other things. Because of such multiple functions, it seems reasonable to propose that changes in temperature also might influence affective and perceptual states. This has been shown to be the case in other situations involving thermal stress. For example, Petruzzello, et al. (1993) showed that 30 minutes of treadmill running, which increased core temperature in excess of 1.6°C, resulted in elevated anxiety. White, et al. (1989) also noted significant relationships between increases in core temperature and skin temperature and increases in thermal sensations. Finally, Maw, et al. (1993) showed that the ability to accurately rate exertion may be confounded when a significant thermal load is added to that provided by exercise. Specifically, Maw, et al. showed that subjects reported lower levels of exertion when their temperature was significantly elevated than would be expected based on their actual heart rate. In other words, the relationship between heart rate and perceived exertion was altered under thermal stress, a point that could have important implications for firefighters.
Given the above findings, we felt it was important to begin to understand (a) what kinds of psychological responses firefighters had to a standardized physical workload and (b) whether these responses differed depending on the type of clothing configuration worn.
STUDY PROTOCOL
As we reported in Fire Engineering, 16 male firefighters were tested under laboratory conditions (Smith, et al., see reference). Each performed a standardized treadmill walking protocol whereby the firefighter walked at a constant speed and elevation (3.5 km/hr -1 at 10 percent grade) for 15 minutes. On separate days, the subjects wore (a) “station blues,” (b) a hip-boot configuration (turnout gear typically worn prior to proposal of the NFPA 1500 standard in 1987), and (c) “NFPA 1500 standard” gear.
Selected psychological measurements were obtained throughout the testing protocol. Ratings of perceived exertion (RPE) were assessed using Borg`s 15-point RPE scale, which has descriptors anchoring the odd values beginning at 7 (very, very light) and continuing through 19 (very, very hard) (see Figure 1). RPE reflects the subject`s judgment of his effort during physical work. Perceptions of respiration were measured using a seven-point scale, with verbal descriptors anchoring the odd values–e.g., 1 = “My breathing is okay right now” and 7 = “I can`t breathe” (see Figure 2). This scale was developed to assess the degree of difficulty in breathing, particularly toward the end of the test. Scores from 5 to 7 on this scale reflect respiratory distress (e.g., not getting enough air, can`t breathe).
Perceptions of thermal sensations were assessed using a nine-point rating scale developed by Young, et al. (1987), which ranged from 0 (unbearably cold) to 4 (comfortable) to 8 (unbearably hot) in one-point increments (see Figure 3). This reflects the degree to which perceived temperature was affected by the different types of turnout gear.
Finally, to get a sense of how the subjects were feeling during the task, ratings were obtained using the Feeling Scale, an 11-point scale that ranges from +5 (feel very good) through 0 (neutral) to -5 (feel very bad) (see Figure 4). Although perceptions of effort and strain were assessed through RPE, this may not indicate how an individual feels during the activity. The Feeling Scale allowed us to assess these feelings.
TEST RESULTS
As was the case with the physiological variables, all of the psychological variables were affected by the type of clothing configuration worn. The NFPA 1500 gear resulted in greater respiratory distress than either of the other clothing conditions. However, the mean score of 2.4 suggests only that the subjects were beginning to breathe hard, not that they were experiencing respiratory distress. Thus, breathing was perceived as more difficult in the NFPA 1500 gear than in the hip-boot gear and station blues. Although breathing did not become problematic in this study, it conceivably could be a problem in a more intense, longer-duration situation.
Based on ratings of thermal sensations, subjects perceived significantly greater heat stress in the NFPA 1500 gear than in the hip-boot gear. By the end of exercise, subjects rated their sensations as “hot” when wearing bunker gear, whereas they rated themselves as “warm” in the hip-boot condition. Interestingly, there was also a slower return toward initial perceptions following the walk in the NFPA 1500 gear, suggesting an impaired ability to dissipate the heat built up during the physical task.
RPE increased in all three conditions from the beginning to end of the task. Again, however, walking in the NFPA 1500 gear was rated as requiring significantly more effort than walking in either of the other two conditions. When asked to rate how they felt during the testing, subjects showed a greater decline in their positive feelings when walking in the NFPA 1500 gear. Further, although they reported a return to feeling good during recovery, this rating was below the initial levels reported at the start of the session. This is in contrast to the hip-boot and station-blues conditions, where they did return to their initial feeling level.
One of the striking aspects of the data was the similarity between the psychological responses reported here and the physiological responses reported earlier. In essence, from a perceptual and self-report perspective, the subjects reflected the increased stress of performing the same physical task in different types of turnout gear. As the level of encapsulation increased from the station-blues uniform to the hip-boot uniform to the NFPA 1500 uniform, the level of perceptual and psychological distress increased incrementally. Not only did the NFPA 1500 gear result in greater distress during the walking task, such distress took a longer time to abate once the physical work was over. Not only did feelings and thermal sensations follow a different trajectory during recovery, but both never returned to initial levels once the workload ended. Finally, as reflected by the physiological responses in the different conditions, subjects perceived the work as requiring significantly more effort while wearing the NFPA 1500 gear. Whether this occurred in combination with the additional perceived heat load or as a result of the more cumbersome NFPA gear (particularly the bunker pants) is unknown, but this needs to be a consideration when work is done in a more “real-world” situation (e.g., fire suppression).
The additional physiological and psychological costs of the NFPA 1500 gear may require either shorter work/longer rest cycles and/or other measures, such as increased aerobic fitness, to reduce the negative effects of the additional protection against burns. n
References
Maw, G.J., S.H. Boutcher, N.A.S. Taylor (1993). “Ratings of perceived exertion and affect in hot and cool environments.” European Journal of Applied Physiology, 67, 174-179.
Petruzzello, S.J., D.M. Landers, W. Salazar (1993). “Exercise and anxiety reduction: examination of temperature as an explanation for affective change.” Journal of Sport & Exercise Psychology, 15, 63-76.
Smith, D.L., S.J. Petruzzello, J.M. Kramer, et al. (1995). “Selected physiological and psychobiological responses to physical activity in different configurations of firefighting gear.” Ergonomics, 38, 2065-2077.
United States Fire Administration (July 1992). Emergency incident report, FA-114.
White, M.K., T.K. Hodous, M. Vercruyssen (1989). “Effects of environment and chemical protective clothing on work tolerance, physiological responses, and subjective ratings.” Ergonomics, 32, 1111-1123.
Young, A.J., M.N. Sawka, Y. Epstein, et al. (1987). “Cooling different body surfaces during upper and lower body exercise.” Journal of Applied Physiology, 63, 1218-1223.
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STEVEN J. PETRUZZELLO, Ph.D., is assistant professor in the Department of Kinesiology at the University of Illinois at Urbana.
DENISE L. SMITH, Ph.D., is assistant professor at Skidmore College, Saratoga Springs, New York, and visiting assistant professor in the Department of Kinesiology at the University of Illinois Fire Service Institute in Urbana.
DAVID F. CLARK, F.F., M.Ed., is staff instructor at the University of Illinois Fire Service Institute in Champaign.
BRADLEY G. BONE, F.F., R.N., is field staff instructor at the University of Illinois Fire Service Institute in Champaign.
