Firefighting Induces Acute Inflammatory Responses that are not Relieved by Aspirin in Older Firefighters

Quantifying self-contained breathing apparatus on physiology and psychological responses during firefighting: a systematic review and meta-analysis

Objectives. There is no consensus regarding the efficacy of self-contained breathing apparatus (SCBA) on firefighters' physiological and psychological stress responses. This study synthesized and quantified the psycho-physiological demands placed on firefighters wearing SCBA compared to a control group. Methods. Five databases were searched with English-language restrictions from inception to January 2021. As dependent variables, physiological (rectal temperature [T_re], mean skin temperature [T¯sk], heart rate [HR], maximal heart rate [HR_max], maximum oxygen uptake [V_O2max], total sweat rate [TSR]) and psychological (rating of perceived exertion [RPE] and thermal sensation [TS]) responses were continuously collected. This study is registered with PROSPERO (CRD42021228363). Results. Nine eligible studies with 289 participants met the inclusion criteria. The pooled estimates for V_O2max statistically significantly decreased, whereas T¯sk, HR, HR_max, TSR and RPE increased significantly. Additionally, the T_re and TS parameters were elevated but not significant. Subgroup analysis revealed that, except for V_O2max and TSR, the SCBA weight did not differ significantly between groups on any outcome measure. Conclusions. Our meta-analysis indicates that wearing SCBA elicits thermoregulatory, metabolic and psychological stress. However, this is not primarily explained by the weight of SCBA, highlighting the value of ergonomic design and physiological monitoring.

Risk Factors for Cardiometabolic Disease in Professional Firefighters

OBJECTIVE

Firefighters are plagued with cardiometabolic disease (CMD). Obesity, poor cardiorespiratory and muscular fitness, and blood lipids (low-density lipoprotein cholesterol, triglycerides, low high-density lipoprotein cholesterol) are risk factors for CMD. However, markers of oxidative stress, inflammation, and insulin resistance can provide further insight regarding CMD risk.

METHODS

This study investigated the relationships between fitness metrics (cardiorespiratory and muscular fitness, percent body fat, waist circumference), blood lipids, blood pressure, and years of experience as a firefighter to blood markers of insulin resistance: Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), oxidative stress: advanced oxidation protein products (AOPPs), and inflammation: C-reactive protein.

RESULTS

Waist circumference and blood concentrations of triglycerides were significantly related to AOPPs and HOMA-IR. Cardiorespiratory fitness was inversely related to AOPPs, HOMA-IR and C-reactive protein.

CONCLUSION

These findings demonstrate the importance of high cardiorespiratory fitness and low waist circumference to reduce markers of CMD.

Lifestyle and environmental factors may induce airway and systemic inflammation in firefighters

Health status depends on multiple genetic and non-genetic factors. Nonheritable factors (such as lifestyle and environmental factors) have stronger impact on immune responses than genetic factors. Firefighters work is associated with exposure to air pollution and heat stress, as well as: extreme physical effort, mental stress, or a changed circadian rhythm, among others. All these factors can contribute to both, short-term and long-term impairment of the physical and mental health of firefighters. Increased levels of some inflammatory markers, such as pro-inflammatory cytokines or C-reactive protein (CRP) have been observed in firefighters, which can lead to local, acute inflammation that promotes a systemic inflammatory response. It is worth emphasizing that inflammation is one of the main hallmarks of cancer and also plays a key role in the development of cardiovascular and respiratory diseases. This article presents possible causes of the development of an inflammatory reaction in firefighters, with particular emphasis on airway inflammation caused by smoke exposure.

Coronary Calcium Scanning and Cardiovascular Risk Assessment Among Firefighters

INTRODUCTION

Sudden cardiac death is the main cause of death among firefighters. The goal of this study is to identify firefighters at risk for cardiovascular disease using coronary artery calcium screening.

METHODS

Asymptomatic firefighters aged ≥40 years without known cardiovascular disease or diabetes (N=487) were recruited from fire departments in 3 Maryland counties from 2016 to 2018, with data analysis from 2018 to 2019. The cardiovascular disease prevention program included an evaluation of blood pressure, cholesterol, BMI, fasting glucose, medications, and a coronary calcium scan. A subset (n=100) was evaluated in more detail, including family history, metabolic syndrome, diet, exercise, smoking, and atherosclerotic cardiovascular disease risk score.

RESULTS

Results indicated that 191 (39%) firefighters had a coronary artery calcium score >0, of which 91% were above the average for age, sex, and ethnicity. On univariable logistic regression, older age, male sex, hypertension, BMI, and glucose were significantly (p<0.05) associated with a higher likelihood of having any coronary artery calcium. Multiple logistic regression found that older age; male sex; taking lipid-lowering or antihypertensive medications; and higher low-density lipoprotein cholesterol, BMI, and fasting blood glucose were significantly associated with a higher likelihood of having coronary artery calcium. Of those with coronary artery calcium, 141 (74%) were not on lipid-lowering medication. In addition, 47 (94%) of those on lipid-lowering medication had a low-density lipoprotein cholesterol >70 mg/dL. In the detailed subset, 30 (30%) had coronary artery calcium. Among these, 28 (93%) had an atherosclerotic cardiovascular disease risk score <7.5%. Thus, if atherosclerotic cardiovascular disease scores alone were used to assess risk in this subset, an opportunity would have been missed to identify and treat firefighters who may have benefited from more aggressive treatment.

CONCLUSIONS

A coronary artery calcium scan may identify the firefighters at increased risk for cardiovascular disease. A comprehensive cardiovascular disease prevention program implemented early in a firefighter's career may help reduce cardiovascular disease risk and thus death and disability in this high-risk population.

Urinary biohazard markers in firefighters

Firefighters are the professional force at high risk of suffering potential health consequences due to their chronic exposure to numerous hazardous pollutants during firefighting activities. Unfortunately, determination of fire emission exposure is very challenging. As such, the identification and development of appropriate biomarkers is critical in meeting this need. This chapter presents a critical review of current information related with the use of different urinary biomarkers of effect and exposure in occupationally exposed firefighters over the last 25 years. Evidence suggests that urinary isoprostanes and mutagenicity testing are promising biomarkers of early oxidative stress. Data indicate that firefighters participating in firefighting activities present with increased urinary biomarkers of exposure. These include polycyclic aromatic hydrocarbons, heavy metals and metalloids, organo-chlorine and -phosphorus compounds, environmental phenols, phthalates, benzene and toluene. More studies are urgently needed to better evaluate firefighter occupational safety and health and to support the implementation of preventive measures and mitigation strategies to promote the protection of this chronically exposed group of workers.

Firefighters' occupational exposure: Contribution from biomarkers of effect to assess health risks

Firefighting is physically and physiologically exhausting besides encompassing exposure to toxic fire emissions. Biomonitoring studies from the past five years have been significantly contributing to characterize the occupational-related health effects in this group of professionals and to improve risk assessment. Therefore, this study gathers and critically discusses the most characterized biomarkers of effect (oxidative stress, DNA and protein damage, stress hormones, inflammation, and vascular, lung, and liver injury), including those potentially more promising to be explored in future studies, and their relation with health outcomes. Various studies proved an association between exposures to fire emissions and/or heat and significantly altered values of biomarkers of inflammation (soluble adhesion molecules, tumor necrosis factor, interleukins, and leucocyte count), vascular damage and tissue injury (pentraxin-3, vascular endothelial growth factor, and cardiac troponin T) in firefighting forces. Moreover, preliminary data of DNA damage in blood, urinary mutagenicity and 8-isoprostaglandin in exhaled breath condensate suggest that these biomarkers of oxidative stress should be further explored. However, most of the reported studies are based on cross-sectional designs, which limit full identification and characterization of the risk factors and their association with development of work-related diseases. Broader studies based on longitudinal designs and strongly supported by the analysis of several types of biomarkers in different biological fluids are further required to gain deeper insights into the firefighters occupational related health hazards and contribute to implementation of new or improved surveillance programs.

Are Inflammatory Markers an Indicator of Exposure or Effect in Firefighters Fighting a Devastating Wildfire? Follow-up of a Cohort in Alberta, Canada

Objectives

The Fort McMurray fire in Alberta, Canada, devastated the townsite in May 2016. First responders were heavily exposed to smoke particles. Blood samples taken from firefighters in May and August/September 2016 were used to measure concentrations of inflammatory markers in plasma and the relation of these markers to exposures and respiratory ill-health.

Methods

Blood samples were drawn from firefighters from two fire services, who also completed questionnaires about tasks and exposures during their deployment to the fire and about respiratory symptoms. Plasma was analysed for 42 inflammatory markers in a multiplex assay. At Service A, samples were collected twice, within 19 days of the start of the fire (early sample) and again 14–18 weeks later (late sample). At Service B, only late samples were collected, at 16–20 weeks. Principal component (PC) scores were extracted from markers in plasma from the early and late samples and, at both time periods, the first two components retained. PC scores were examined against estimated cumulative exposures to PM_2.5 particles, self-rated physical stressors during the fire, and time since the last deployment to an active fire. The relation of component scores and exposure estimates to respiratory health were examined, using self-ratings at the time of the blood draw, a validated respiratory screening questionnaire (the European Community Respiratory Health Survey [ECRHS]) some 30 months after the fire, and clinical assessments in 2019–2020.

Results

Repeat blood samples were available for 68 non-smoking first responders from Service A and late samples from 160 non-smokers from both services. In the 68 with two samples, marker concentrations decreased from early to late samples for all but 3 of the 42 markers, significantly so (P < 0.05) for 25. The first component extracted from the early samples (C1E) was unrelated to respiratory symptoms but the second (C2E) was weakly related to increased cough (P = 0.079) and breathlessness (P = 0.068) and a lower forced expiratory volume in one second/forced expiratory capacity (FEV₁/FVC)(β = –1.63, 95% CI –3.11 to –0.14) P = 0.032. The first PC at 14–20 weeks (C1L) was unrelated to exposure or respiratory health but the second PC (C2L) from these late samples, drawn from both fire services, related to cumulative PM_2.5 exposure. In a multivariate model, clustered within fire service, cumulative exposure (β = 0.19, 95% CI 0.09–0.30), dehydration (β = 0.65, 95% CI 0.04–1.27) and time since last deployed to a fire (β = –0.04, 95% CI –0.06 to –0.01) were all related to the C2L score. This score was also associated with respiratory symptoms of wheezing, chest tightness, and breathlessness at the time of the blood draw but not to symptoms at later follow-up. However, apart from the lower FEV₁/FVC at 15–19 days, the marker scores did not add to regression models that also included estimated cumulative PM_2.5 exposure.

Conclusions

Concentrations of persisting inflammatory markers in the plasma of firefighters deployed to a devastating fire decreased with time and were related to estimates of exposure. Although not a powerful independent predictor of later respiratory ill-health, they may serve as an indicator of previous high exposure in the absence of contemporary exposure estimates.