Current guidelines from NFPA 1584 recommend that firefighters (FF) should receive onscene rehabilitation after strenuous firefighting activity before continuing work. However, controversy exists as to what physiological variables, and associated values, should be used to determine when it is medically safe to allow a firefighter to resume physical exertion. PURPOSE: The purpose of this study was to document changes in physiological measurements (HR, Tco, Tskin, BP, SpO2, SpC0) during 10 minutes of on-scene rehabilitation following firefighting activity. METHODS: Male FF (n=56) between 18 and 50 yrs who were free of known CVD participated in 18 minutes of simulated firefighting activity (stair climbing, forcible entry, searching, and advancing a fire hose) in a training structure that contained live fires. After exiting the firefighting course and completing some additional testing, FF reported to the REHAB sector, arriving an average of 9:30 min after exiting the course. Once in rehab, participants doffed their gear and were provided with water and passive cooling. Data was recorded immediately upon entering rehab, at 5 and 10 min after entry. RESULTS: Participants were relatively young (26.5 ± 6.7 yrs) and had largely homogenous descriptive variables. On average FF entered rehab with a mean HR of 122 b[[Unsupported Character - ·]]min−1, and this value decreased to 101 b[[Unsupported Character - ·]]min−1 after 10 min. in rehab. FF entered rehab with a Tco of 38.0 °C and this value decreased to 36.7 °C following 10 min. SBP averaged 125 mmHg upon entering and decreased to 117 mmHg following rehab. Three of the FF who completed the firefighting activity presented with signs or symptoms (pale, nausea) of heat illness and were actively cooled. Two FF entered rehab with SBP >150 mmHg but both of these returned to less than 140 mmHg following rehab. Two FFs experiencing signs of hypotension upon entrance to REHAB were monitored closely and one was held past the 10 min period. CONCLUSION: During the 10 min in the rehab area HR, Tco, and SBP all decreased significantly. However, even in this group of young, healthy men, HR was slightly above 100 b[[Unsupported Character - ·]]min−1, a value often utilized in departmental policies, following rehab. This study was supported by DHS AFG EMW-2006-FP-02459
This study examined the effects of moderate exercise-induced heat stress (EIHS) on vascular function, central hemodynamic load and indices of coronary perfusion. Vascular-hemodynamic measures were collected in 12 healthy men (aged 22±3 years) pre and post 100 minutes of moderate, intermittent exercise in two randomized conditions: heat stress (HS; wearing firefighter personal protective equipment (PPE)), and no heat stress (NHS; wearing a cooling shirt and equivalent PPE weight). Aortic blood pressure, reflected wave pressure (Pb), systolic (SPTI) and diastolic pressure time-integral (DPTI), and aortic stiffness were assessed before and after each condition. SPTI was significantly greater, and DPTI and Pb were significantly lower for HS-post compared to NHS-post ( p<0.05). Pulse wave velocity was not different between conditions. In conclusion, EIHS does not affect aortic stiffness, but increases indices of myocardial work and reduces indices of coronary perfusion which may be related to chronotropic responses to EIHS. The mismatch between oxygen demand and oxygen supply may increase cardiac vulnerability to ischemia during strenuous work in the heat.
Abstract Background Research consistently finds that, on average, firefighters gain weight over time and some data indicate that younger firefighters are more likely to gain weight than older firefighters. The purpose of this study was to estimate the 5-year weight change among younger and older US firefighters. Methods Data from two occupational medical exams separated by 5 years (2009–2016) were examined from a cohort of US career firefighters in Virginia (males, n = 589; females, n = 67). The cohort was grouped into two age categories (< 45 years and ≥ 45 years). Weight change subgroups were Loss (decrease of > 3% body weight), Stable (within ±3% body weight) and Gain (increase of > 3% body weight). Multinomial logistic regression models and linear regression models were conducted to examine differences in the probability of being in a particular weight change category, weight change overall and by weight change category between younger and older firefighters. Results At baseline, 25 and 35% of younger (< 45 years) and older (≥ 45 years) were obese, respectively. Younger firefighters gained significantly ( P < 0.05) more weight (3.0 ± 0.2 kg) than older firefighters (0.8 ± 0.5 kg). Younger firefighters were more likely to gain weight (53% versus 39%) and less likely (10% versus 20%) to lose weight as compared to older firefighters. Smaller weight gains were associated with age and BMI with the smallest increases observed in overweight and obese firefighters ≥45 years of age. Conclusions Health care providers should be attentive to weight gain, even among young non-obese firefighters, and counsel firefighters to avoid the additive risks of being older and heavier. In addition, weight loss/management programs should be promoted in the fire service to encourage healthy body weight and to prevent unhealthy weight gain among both young and old firefighters alike.
In this study, we characterize the area and personal air concentrations of combustion byproducts produced during controlled residential fires with furnishings common in 21st century single family structures. Area air measurements were collected from the structure during active fire and overhaul (post suppression) and on the fireground where personnel were operating without any respiratory protection. Personal air measurements were collected from firefighters assigned to fire attack, victim search, overhaul, outside ventilation, and command/pump operator positions. Two different fire attack tactics were conducted for the fires (6 interior and 6 transitional) and exposures were compared between the tactics. For each of the 12 fires, firefighters were paired up to conduct each job assignment, except for overhaul that was conducted by 4 firefighters. Sampled compounds included polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs, e.g., benzene), hydrogen cyanide (HCN), and particulate (area air sampling only). Median personal air concentrations for the attack and search firefighters were generally well above applicable short-term occupational exposure limits, with the exception of HCN measured from search firefighters. Area air concentrations of all measured compounds decreased after suppression. Personal air concentrations of total PAHs and benzene measured from some overhaul firefighters exceeded exposure limits. Median personal air concentrations of HCN (16,300 ppb) exceeded the exposure limit for outside vent firefighters, with maximum levels (72,900 ppb) higher than the immediately dangerous to life and health (IDLH) level. Median air concentrations on the fireground (including particle count) were above background levels and highest when collected downwind of the structure and when ground-level smoke was the heaviest. No statistically significant differences in personal air concentrations were found between the 2 attack tactics. The results underscore the importance of wearing self-contained breathing apparatus when conducting overhaul or outside ventilation activities. Firefighters should also try to establish command upwind of the structure fire, and if this cannot be done, respiratory protection should be considered.
Previous reports indicate that the "athlete's heart" is more prominent in males than females, but the mechanisms responsible for this sex difference have not been elucidated. This study examined male-female differences in cardiac mass and volume in highly trained athletes and normally active individuals to assess the relative contributions of pre-existing sex differences and sports training to cardiac findings.Echocardiographic and electrocardiographic findings were compared between 20 male and 21 female collegiate athletes and 22 male and 29 female normally-active subjects.Cardiac mass (per kg lean body mass) was significantly greater in the male compared to female athletes (3.62±0.55 and 3.31±0.56 g.kg-1, respectively). A similar magnitude of difference in average relative cardiac mass was observed between the normally active males and females, and cardiac mass was greater in athletic versus nonathletic groups by +14.9% in the males and +13.3% in the females. Relative left ventricular volume was greater in the male athletes (47.5±6.3 ml•BSA-1.5) compared to male nonathletes (42.9±6.1 ml•BSA-1.5); no such difference was observed in the females.These findings suggest that sex differences in both the untrained state and magnitude of training response contribute to male-female differences in the "athlete's heart"
Firefighters (FF) routinely perform arduous work in extreme environmental temperatures. However, little is known about the most effective methods to cool, rehydrate and reverse imbalances caused by working in such stressful environments. PURPOSE: To investigate the effects of different On-Scene Rehabilitation (OSR) protocols on subsequent psychological recovery along with cognitive function. METHODS: Male FF (N=17; M age=24.5±4.7 yrs) free of known cardiovascular disease participated in 18 minutes of simulated firefighting (FF) activity (stair climbing, forcible entry, searching, advancing a line) in a training structure that contained live fires wearing standard turnout gear and an air pack on 2 separate days. During the "control" trial (meant to reflect OSR typically done at a fire scene), following simulated FF activity FFs removed their helmet, hood, gloves, and bunker coat and were provided with only water. During the "enhanced" OSR trial, following simulated FF activity FFs removed all of turn-out gear (including bunker coat, pants), consumed 1 L of water and 0.5 L of sport drink, and were aggressively cooled using a misting fan or cold towels. Psychological (AD ACL) and cognitive function measures [reaction times (RT) on a decision-making task] were obtained immediately before and after FF activities and following 2 hrs of recovery. RESULTS: Firefighting activity resulted in significant increases in Energy (+1.9 units) and Tension (+0.7 units) along with significant decreases in Tiredness (-1.9 units) and Calmness (-2.5 units) from pre- to post-activity, with subsequent returns to pre-activity levels after recovery. RTs were significantly faster following activity (-25.2 msec), and then returned to pre-activity level by 2 hrs post-activity. There were no significant differences between the OSR protocols. CONCLUSION: Firefighting resulted in significant changes in psychological and cognitive function measures; however, the effect of different OSR was negligible compared to the effects of the firefighting activity itself. Supported by NIOSH Grant R03 OH009111-01.
An extensive surveillance program has been maintained since 1951 to determine the concentrations of radionuclides in a 1200 square mile area in the environs of the plant and the radiation exposure of the population resulting from SRP operations. This document summarizes the 1979 results. The radiation dose at the plant perimeter and the population dose in the region from SRP operations are very small relative to the dose recieved from naturally occurring radiation. The annual average dose in 1979 from atmospheric releases of radioactive materials was 0.71 mrem at the perimeter (1% of natural background). The maximum dose at the plant perimeter was 0.97 mrem. Air and water are the major dispersal media for radioactive emissions. Samples representing most segments of the environment were monitored. Releases of radioactivity from SRP had a very small effect on living plants and animals and were too minute to be detectable, and with a few exceptions, concentrations outside the plant boundary were too low to distinguish from the natural radioactive background and continuing worldwide fallout from nuclear weapons tests. 40 figures, 60 tables. (MF)
The international fire service community is actively engaged in a wide range of activities focused on development, testing, and implementation of effective approaches to reduce exposure to contaminants and the related cancer risk. However, these activities are often viewed independent of each other and in the absence of the larger overall effort of occupational health risk mitigation. This narrative review synthesizes the current research on fire service contamination control in the context of the National Institute for Occupational Safety and Health (NIOSH) Hierarchy of Controls, a framework that supports decision making around implementing feasible and effective control solutions in occupational settings. Using this approach, we identify evidence-based measures that have been investigated and that can be implemented to protect firefighters during an emergency response, in the fire apparatus and at the fire station, and identify several knowledge gaps that remain. While a great deal of research and development has been focused on improving personal protective equipment for the various risks faced by the fire service, these measures are considered less effective. Administrative and engineering controls that can be used during and after the firefight have also received increased research interest in recent years. However, less research and development have been focused on higher level control measures such as engineering, substitution, and elimination, which may be the most effective, but are challenging to implement. A comprehensive approach that considers each level of control and how it can be implemented, and that is mindful of the need to balance contamination risk reduction against the fire service mission to save lives and protect property, is likely to be the most effective.
