Exposures and cross-shift lung function declines in wildland firefighters

Cross-shift changes in pulmonary function and occupational exposure to particulate matter among e-waste workers in Ghana

Introduction

Little is known on the association between cross-shift changes in pulmonary function and personal inhalation exposure to particulate matter (PM) among informal electronic-waste (e-waste) recovery workers who have substantial occupational exposure to airborne pollutants from burning e-waste.

Methods

Using a cross-shift design, pre- and post-shift pulmonary function assessments and accompanying personal inhalation exposure to PM (sizes <1, <2.5 μm, and the coarse fraction, 2.5-10 μm in aerodynamic diameter) were measured among e-waste workers (n = 142) at the Agbogbloshie e-waste site and a comparison population (n = 65) in Accra, Ghana during 2017 and 2018. Linear mixed models estimated associations between percent changes in pulmonary function and personal PM.

Results

Declines in forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) per hour were not significantly associated with increases in PM (all sizes) among either study population, despite breathing zone concentrations of PM (all sizes) that exceeded health-based guidelines in both populations. E-waste workers who worked "yesterday" did, however, have larger cross-shift declines in FVC [-2.4% (95%CI: -4.04%, -0.81%)] in comparison to those who did not work "yesterday," suggesting a possible role of cumulative exposure.

Discussion

Overall, short-term respiratory-related health effects related to PM exposure among e-waste workers were not seen in this sample. Selection bias due to the "healthy worker" effect, short shift duration, and inability to capture a true "pre-shift" pulmonary function test among workers who live at the worksite may explain results and suggest the need to adapt cross-shift studies for informal settings.

Exploring the adverse effect of fine particulate matter (PM2.5) on wildland firefighters' pulmonary function and DNA damage

Chiang Mai encounters severe pollution during the wildfire season. Wildland firefighters encounter various hazards while engaged in fire suppression operations, which encompass significant exposure to elevated concentrations of air pollutants resulting from combustion, especially particulate matter. The adverse effects of wildfire smoke on respiratory health are a significant concern. The objective of this study was to examine the potential adverse effects of PM2.5 exposure on the respiratory function and DNA damage of wildland firefighters. This prospective cohort study conducted in Chiang Mai from January to May 2022 planned to evaluate the health status of wildland firefighters during the pre-peak, peak, and post-peak ambient air pollution seasons. The measurement of PM2.5 was done at every forest fire station, as well as utilizing data from the Pollution Control Department. Participants received general health examinations, spirometry evaluations, and blood tests for DNA damage analysis. Pair t-tests and multiple regression models were used to examine the connection between pulmonary function parameters (FVC, FEV1) and PM2.5 concentration, with a significance level of P < 0.05. Thirty-three peak-season and twenty-one post-peak-season participants were enrolled. Four pre-peak-season wildland firefighters had FVC and FEV1 declines of > 15%. Multiple regression analysis showed a negative association between PM2.5 exposure and FVC% predicted (- 2.81%, 95% CI - 5.27 to - 0.34%, P = 0.027) and a marginally significant negative correlation with FVC (- 114.38 ml, 95% CI - 230.36 to 1.59 ml, P = 0.053). The remaining pulmonary measures showed a statistically insignificant decline. There were no significant changes in DNA damage detected. Wildland firefighters suffered a significant decline in pulmonary function associated with PM2.5 exposure. Spirometry is crucial for monitoring and promptly identifying respiratory issues that occur during wildfire seasons. Further research is recommended to explore DNA damage alterations and their potential association with PM2.5.

Health Effects of Wildfire Smoke Exposure

We review current knowledge on the trends and drivers of global wildfire activity, advances in the measurement of wildfire smoke exposure, and evidence on the health effects of this exposure. We describe methodological issues in estimating the causal effects of wildfire smoke exposures on health and quantify their importance, emphasizing the role of nonlinear and lagged effects. We conduct a systematic review and meta-analysis of the health effects of wildfire smoke exposure, finding positive impacts on all-cause mortality and respiratory hospitalizations but less consistent evidence on cardiovascular morbidity. We conclude by highlighting priority areas for future research, including leveraging recently developed spatially and temporally resolved wildfire-specific ambient air pollution data to improve estimates of the health effects of wildfire smoke exposure.

Characterization of inhalation exposures at a wildfire incident during the Wildland Firefighter Exposure and Health Effects (WFFEHE) Study

Wildland firefighters (WFFs) are exposed to many inhalation hazards working in the wildland fire environment. To assess occupational exposures and acute and subacute health effects among WFFs, the wildland firefighter exposure and health effects study collected data for a 2-year repeated measures study. This manuscript describes the exposure assessment from one Interagency Hotshot Crew (N = 19) conducted at a wildfire incident. Exposures to benzene, toluene, ethylbenzene, xylene isomers, formaldehyde, acetaldehyde, and naphthalene were measured through personal air sampling each work shift. Biological monitoring was done for creatinine-adjusted levoglucosan in urine pre- and post-shift. For 3 days sampling at the wildfire incident, benzene, toluene, ethylbenzene, xylene isomers (m and p, and o) exposure was highest on day 1 (geometric mean [GM] = 0.015, 0.042, 0.10, 0.42, and 0.15 ppm, respectively) when WFFs were not exposed to smoke but used chainsaws to remove vegetation and prepare fire suppression breaks. Exposure to formaldehyde and acetaldehyde was highest on day 2 (GM = 0.03 and 0.036 ppm, respectively) when the WFFs conducted a firing operation and were directly exposed to wildfire smoke. The greatest difference of pre- and post-shift levoglucosan concentrations were observed on day 3 (pre-shift: 9.7 and post-shift: 47 μg/mg creatinine) after WFFs conducted mop up (returned to partially burned area to extinguish any smoldering vegetation). Overall, 65% of paired samples (across all sample days) showed a post-shift increase in urinary levoglucosan and 5 firefighters were exposed to benzene at concentrations at or above the National Institute for Occupational Safety and Health (NIOSH) recommended exposure limit. Our findings further demonstrate that exposure to inhalation hazards is one of many risks that wildland firefighters experience while suppressing wildfires.

Longitudinal lung function in urban firefighters: A group-based multi-trajectory modelling approach

BACKGROUND AND OBJECTIVE

Urban firefighters are routinely exposed to both physical and chemical hazards that can negatively impact lung health, but it is unclear if firefighters experience accelerated decline in spirometry parameters due to chronic exposure and acute insults. This study aimed to describe sub-groups of firefighters with differing spirometry trajectories and examine the relationship between the identified trajectories and demographic, lifestyle and occupational characteristics.

METHODS

Data from six waves of the Respiratory Function Measurement and Surveillance for South Australian Metropolitan Fire Service Study (2007-2019) were used to identify spirometry parameter z-score trajectories, using group-based multi-trajectory modelling (GBMTM). Analysis of variance and chi-square statistics were used to assess trajectory group differences in baseline self-reported demographic, lifestyle and occupational characteristics.

RESULTS

In the 669 included firefighters, we identified five trajectories for the combination of Forced Expiratory Volume in the first second z-score (FEV₁ z), Forced Vital Capacity z-score (FVCz) and the ratio of FEV₁ and FVC z-score (FEV₁ /FVCz). There were three stable trajectories of low, average and very high lung function and two declining trajectories of average and high lung function. Analysis of subgroup characteristics revealed no significant differences between expected and actual group proportions for the occupational characteristics of years of service and respiratory protection use. Significant differences were seen in respiratory health and body mass index.

CONCLUSION

GBMTM defined distinct, plausible spirometry trajectory sub-groups. Firefighter longitudinal spirometry trajectory group membership was associated with BMI and respiratory disease or symptoms but not with self-reported smoking history or occupational factors.

Prolonged smoldering Douglas fir smoke inhalation augments respiratory resistances, stiffens the aorta, and curbs ejection fraction in hypercholesterolemic mice

While mounting evidence suggests that wildland fire smoke (WFS) inhalation may increase the burden of cardiopulmonary disease, the occupational risk of repeated exposure during wildland firefighting remains unknown. To address this concern, we evaluated the cardiopulmonary function in mice following a cumulative exposure to lab-scale WFS equivalent to a mid-length wildland firefighter (WLFF) career. Dosimetry analysis indicated that 80 exposure hours at a particulate concentration of 22 mg/m3 yield in mice the same cumulative deposited mass per unit of lung surface area as 3600 h of wildland firefighting. To satisfy this condition, male Apoe-/- mice were whole-body exposed to either air or smoldering Douglas fir smoke (DFS) for 2 h/day, 5 days/week, over 8 consecutive weeks. Particulate size in DFS fell within the respirable range for both mice and humans, with a count median diameter of 110 ± 20 nm. Expiratory breath hold in mice exposed to DFS significantly reduced their minute volume (DFS: 27 ± 4; Air: 122 ± 8 mL/min). By the end of the exposure time frame, mice in the DFS group exhibited a thicker (DFS: 109 ± 3; Air: 98 ± 3 μm) and less distensible (DFS: 23 ± 1; Air: 28 ± 1 MPa-1) aorta with reduced diastolic blood augmentation capacity (DFS: 53 ± 2; Air: 63 ± 2 kPa). Cardiac magnetic resonance imaging further revealed larger end-systolic volume (DFS: 14.6 ± 1.1; Air: 9.9 ± 0.9 μL) and reduced ejection-fraction (DFS: 64.7 ± 1.0; Air: 75.3 ± 0.9 %) in mice exposed to DFS. Consistent with increased airway epithelium thickness (DFS: 10.4 ± 0.8; Air: 7.6 ± 0.3 μm), airway Newtonian resistance was larger following DFS exposure (DFS: 0.23 ± 0.03; Air: 0.20 ± 0.03 cmH2O-s/mL). Furthermore, parenchyma mean linear intercept (DFS: 36.3 ± 0.8; Air: 33.3 ± 0.8 μm) and tissue thickness (DFS: 10.1 ± 0.5; Air: 7.4 ± 0.7 μm) were larger in DFS mice. Collectively, mice exposed to DFS manifested early signs of cardiopulmonary dysfunction aligned with self-reported events in mid-career WLFFs.

The Effect of Fire Smoke Exposure on Firefighters' Lung Function: A Meta-Analysis

Firefighters are exposed to a range of harmful substances during firefighting. Exposure to fire smoke has been associated with a decrease in their lung function. However, the cause-effect relationship between those two factors is not yet demonstrated. This meta-analysis aimed to evaluate the potential associations between firefighters' occupational exposure and their lung function deterioration. Studies were identified from PubMed, Web of Science, Scopus and Science Direct databases (August 1990-March 2021). The studies were included when reporting the lung function values of Forced Expiratory Volume in 1 s (FEV₁) or Forced Vital Capacity (FVC). The meta-analyses were performed using the generic inverse variance in R software with a random-effects model. Subgroup analysis was used to determine if the lung function was influenced by a potential study effect or by the participants' characteristics. A total of 5562 participants from 24 studies were included. No significant difference was found between firefighters' predicted FEV₁ from wildland, 97.64% (95% CI: 91.45-103.82%; I² = 99%), and urban fires, 99.71% (95% CI: 96.75-102.67%; I² = 98%). Similar results were found for the predicted FVC. Nevertheless, the mean values of firefighters' predicted lung function varied significantly among studies, suggesting many confounders, such as trials' design, statistical methods, methodologies applied, firefighters' daily exposure and career length, hindering an appropriate comparison between the studies.

Effect of fire spread, flame characteristic, fire intensity on particulate matter 2.5 released from surface fuel combustion of Pinus koraiensis plantation- A laboratory simulation study

PM2.5 is one of major pollutants emitted from forest fires. High PM2.5 concentration not only affects short-term human respiration health, but also poses a long-term threat to human cardiopulmonary functionality. Therefore, it is of great importance to quantitatively assess the PM2.5 released by forest combustion in forest fire studies. In this study we examine relationships between the PM2.5 concentration and environment and fuel characteristics laboratory experiments. In the experiments, fuel beds with controlled moisture contents and loads were first built; then 144 ignition experiments were conducted for various combinations of wind speeds using a wind tunnel device. Fire behavior characteristics and PM2.5 concentrations released from fuel combustion were measured and analyzed. The experimental results show that the relationship between fire characteristics, fire intensity and the influencing factors of wind speed, fuel moisture content, and fuel load can be explained by the fundamental theory of forest combustion. Although PM2.5 concentration rises with the increase of wind speed, the decrease of fuel moisture content, and the increase of fuel load, there appears to be a fuel load threshold for a given combination of wind speed and fuel moisture content that the increase of PM2.5 concentration decelerates quickly after the load passes the threshold value. After screening fire behavior characteristics that affect PM2.5 concentration, we found that fire line intensity and flame width are the ones with the strongest association with the concentration. With flame width as independent variable, we have built two regression models to predict PM2.5 and fire line intensity which are treated as dependent variable; the models have high accuracy with R2 = 0.92 for predicting PM2.5 and R2 = 0.97 for predicting fire line intensity. Study results can be used as reference to protect the health of forest fire fighters, and can be helpful for forest fire smoke management.

The Wildland Firefighter Exposure and Health Effect (WFFEHE) Study: Rationale, Design, and Methods of a Repeated-Measures Study

The wildland firefighter exposure and health effect (WFFEHE) study was a 2-year repeated-measures study to investigate occupational exposures and acute and subacute health effects among wildland firefighters. This manuscript describes the study rationale, design, methods, limitations, challenges, and lessons learned. The WFFEHE cohort included fire personnel ages 18-57 from six federal wildland firefighting crews in Colorado and Idaho during the 2018 and 2019 fire seasons. All wildland firefighters employed by the recruited crews were invited to participate in the study at preseason and postseason study intervals. In 2019, one of the crews also participated in a 3-day midseason study interval where workplace exposures and pre/postshift measurements were collected while at a wildland fire incident. Study components assessed cardiovascular health, pulmonary function and inflammation, kidney function, workplace exposures, and noise-induced hearing loss. Measurements included self-reported risk factors and symptoms collected through questionnaires; serum and urine biomarkers of exposure, effect, and inflammation; pulmonary function; platelet function and arterial stiffness; and audiometric testing. Throughout the study, 154 wildland firefighters participated in at least one study interval, while 144 participated in two or more study interval. This study was completed by the Centers for Disease Control and Prevention's National Institute for Occupational Safety and Health through a collaborative effort with the U.S. Department of Agriculture Forest Service, Department of the Interior National Park Service, and Skidmore College. Conducting research in the wildfire environment came with many challenges including collecting study data with study participants with changing work schedules and conducting study protocols safely and operating laboratory equipment in remote field locations. Forthcoming WFFEHE study results will contribute to the scientific evidence regarding occupational risk factors and exposures that can impact wildland firefighter health over a season and across two wildland fire seasons. This research is anticipated to lead to the development of preventive measures and policies aimed at reducing risk for wildland firefighters and aid in identifying future research needs for the wildland fire community.

Fine Particulate Matter and Lung Function among Burning-Exposed Deepwater Horizon Oil Spill Workers

BACKGROUND

During the 2010 Deepwater Horizon (DWH) disaster, controlled burning was conducted to remove oil from the water. Workers near combustion sites were potentially exposed to increased fine particulate matter [with aerodynamic diameter ≤2.5μm (PM2.5)] levels. Exposure to PM2.5 has been linked to decreased lung function, but to our knowledge, no study has examined exposure encountered in an oil spill cleanup.

OBJECTIVE

We investigated the association between estimated PM2.5 only from burning/flaring of oil/gas and lung function measured 1-3 y after the DWH disaster.

METHODS

We included workers who participated in response and cleanup activities on the water during the DWH disaster and had lung function measured at a subsequent home visit (n=2,316). PM2.5 concentrations were estimated using a Gaussian plume dispersion model and linked to work histories via a job-exposure matrix. We evaluated forced expiratory volume in 1 s (FEV1; milliliters), forced vital capacity (FVC; milliliters), and their ratio (FEV1/FVC; %) in relation to average and cumulative daily maximum exposures using multivariable linear regressions.

RESULTS

We observed significant exposure-response trends associating higher cumulative daily maximum PM2.5 exposure with lower FEV1 (p-trend=0.04) and FEV1/FVC (p-trend=0.01). In comparison with the referent group (workers not involved in or near the burning), those with higher cumulative exposures had lower FEV1 [-166.8mL, 95% confidence interval (CI): -337.3, 3.7] and FEV1/FVC (-1.7, 95% CI: -3.6, 0.2). We also saw nonsignificant reductions in FVC (high vs. referent: -120.9, 95% CI: -319.4, 77.6; p-trend=0.36). Similar associations were seen for average daily maximum PM2.5 exposure. Inverse associations were also observed in analyses stratified by smoking and time from exposure to spirometry and when we restricted to workers without prespill lung disease.

CONCLUSIONS

Among oil spill workers, exposure to PM2.5 specifically from controlled burning of oil/gas was associated with significantly lower FEV1 and FEV1/FVC when compared with workers not involved in burning. https://doi.org/10.1289/EHP8930.

Health risks and mitigation strategies from occupational exposure to wildland fire: a scoping review

OBJECTIVES

Due to accelerating wildland fire activity, there is mounting urgency to understand, prevent, and mitigate the occupational health impacts associated with wildland fire suppression. The objectives of this review of academic and grey literature were to: 1. Identify the impact of occupational exposure to wildland fires on physical, mental, and emotional health; and 2. Examine the characteristics and effectiveness of prevention, mitigation, or management strategies studied to reduce negative health outcomes associated with occupational exposure to wildland fire.

METHODS

Following established scoping review methods, academic literature as well as government and industry reports were identified by searching seven academic databases and through a targeted grey literature search. 4679 articles were screened using pre-determined eligibility criteria. Data on study characteristics, health outcomes assessed, prevention or mitigation strategies studied, and main findings were extracted from each included document. The results of this scoping review are presented using descriptive tables and a narrative summary to organize key findings.

RESULTS

The final sample was comprised of 100 articles: 76 research articles and 24 grey literature reports. Grey literature focused on acute injuries and fatalities. Health outcomes reported in academic studies focused on respiratory health (n = 14), mental health (n = 16), and inflammation and oxidative stress (n = 12). The identified studies evaluated short-term outcomes measuring changes across a single shift or wildland fire season. Most research was conducted with wildland firefighters and excluded personnel such as aviation crews, contract crews, and incident management teams. Five articles reported direct study of mitigation strategies, focusing on the potential usage of masks, advanced hygiene protocols to reduce exposure, fluid intake to manage hydration and core temperature, and glutamine supplementation to reduce fatigue.

CONCLUSIONS

While broad in scope, the evidence base linking wildland fire exposure to any one health outcome is limited. The lack of long-term evidence on changes in health status or morbidity is a clear evidence gap and there is a need to prioritize research on the mental and physical health impact of occupational exposure to wildland fire.

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.

Environmental and Occupational Short-Term Exposure to Airborne Particles and FEV1 and FVC in Healthy Adults: A Systematic Review and Meta-Analysis

Background: No study has compared the respiratory effects of environmental and occupational particulate exposure in healthy adults. Methods: We estimated, by a systematic review and meta-analysis, the associations between short term exposures to fine particles (PM_2.5 and PM₄) and certain parameters of lung function (FEV₁ and FVC) in healthy adults. Results: In total, 33 and 14 studies were included in the qualitative synthesis and meta-analyses, respectively. In environmental studies, a 10 µg/m³ increase in PM_2.5 was associated with an FEV₁ reduction of 7.63 mL (95% CI: −10.62 to −4.63 mL). In occupational studies, an increase of 10 µg/m³ in PM₄ was associated with an FEV₁ reduction of 0.87 mL (95% CI: −1.36 to −0.37 mL). Similar results were observed with FVC. Conclusions: Both occupational and environmental short-term exposures to fine particles are associated with reductions in FEV₁ and FVC in healthy adults.

Chronic Obstructive Pulmonary Disease in Adults Exposed to Fine Particles from a Coal Mine Fire

RATIONALE

In 2014 the Hazelwood open cut coal mine in south eastern Australia burned for six weeks, exposing nearby residents to high concentrations of fine particulate matter (PM_2.5). The long-term health consequences are unknown, and are being evaluated as part of the Hazelwood Health Study.

OBJECTIVES

To explore the association between PM_2.5 exposure and chronic obstructive pulmonary disease (COPD).

METHODS

A sample of 346 exposed, and 173 unexposed, adults participated in the longitudinal Respiratory Stream of the Hazelwood Health Study. Participants underwent spirometry and gas transfer measurements, and answered validated respiratory questionnaires 3.5-4 years after the fire. Individual-level mine fire-related PM_2.5 exposure was modelled. Multivariate linear regression and logistic models were fitted to analyse associations between mean and peak PM_2.5 exposure and clinical outcomes, stratified by smoking status.

RESULTS

A 10 μg/m³ increase in mean PM_2.5 exposure was associated with a 69% (95%CI: 11% to 158%) increase in odds of spirometry consistent with COPD amongst non-smokers and increased odds of chest tightness (odds ratio; OR 1.30, 95%CI 1.03 to 1.64) and chronic cough (OR 1.24, 95%CI 1.02 to 1.51) in the previous 12 months in all participants. For current smokers, increments in mean PM_2.5 exposure were associated with higher odds of chronic cough in the preceding 12 months (OR 2.13, 95%CI 1.24 to 3.65).

CONCLUSIONS

Almost four years after a six-week period of coal fire PM_2.5 exposure, we identified a dose-response association between exposure and COPD in non-smokers. With climate change a likely contributor to increased risk of landscape fires, the findings will inform policy decisions during future sustained smoke events.

Exposure to Particulate Matter and Estimation of Volatile Organic Compounds across Wildland Firefighter Job Tasks

Wildland firefighters are exposed to smoke-containing particulate matter (PM) and volatile organic compounds (VOCs) while suppressing wildfires. From 2015 to 2017, the U.S. Forest Service conducted a field study collecting breathing zone measurements of PM₄ (particulate matter with aerodynamic diameter ≤4 μm) on wildland firefighters from different crew types and while performing various fire suppression tasks on wildfires. Emission ratios of VOC (parts per billion; ppb): PM₁ (particulate matter with aerodynamic diameter ≤1 μm; mg/m³) were calculated using data from a separate field study conducted in summer 2018, the Western Wildfire Experiment for Cloud Chemistry, Aerosol Absorption, and Nitrogen (WE-CAN) Campaign. These emission ratios were used to estimate wildland firefighter exposure to acrolein, benzene, and formaldehyde. Results of this field sampling campaign reported that exposure to PM₄ and VOC varied across wildland firefighter crew type and job task. Type 1 crews had greater exposures to both PM₄ and VOCs than type 2 or type 2 initial attack crews, and wildland firefighters performing direct suppression had statistically higher exposures than those performing staging and other tasks (mean differences = 0.82 and 0.75 mg/m³; 95% confidence intervals = 0.38-1.26 and 0.41-1.08 mg/m³, respectively). Of the 81 personal exposure samples collected, 19% of measured PM₄ exposures exceeded the recommended National Wildland Fire Coordinating Group occupational exposure limit (0.7 mg/m³). Wildland fire management should continue to find strategies to reduce smoke exposures for wildland firefighters.

Wildland firefighter exposure to smoke and COVID-19: A new risk on the fire line

Throughout the United States, wildland firefighters respond to wildfires, performing arduous work in remote locations. Wildfire incidents can be an ideal environment for the transmission of infectious diseases, particularly for wildland firefighters who congregate in work and living settings. In this review, we examine how exposure to wildfire smoke can contribute to an increased likelihood of SARS-CoV-2 infection and severity of coronavirus disease (COVID-19). Human exposure to particulate matter (PM), a component of wildfire smoke, has been associated with oxidative stress and inflammatory responses; increasing the likelihood for adverse respiratory symptomology and pathology. In multiple epidemiological studies, wildfire smoke exposure has been associated with acute lower respiratory infections, such as bronchitis and pneumonia. Co-occurrence of SARS-CoV-2 infection and wildfire smoke inhalation may present an increased risk for COVID-19 illness in wildland firefighters due to PM based transport of SARS CoV-2 virus and up-regulation of angiotensin-converting enzyme II (ACE-2) (i.e. ACE-2 functions as a trans-membrane receptor, allowing the SARS-CoV-2 virus to gain entry into the epithelial cell). Wildfire smoke exposure may also increase risk for more severe COVID-19 illness such as cytokine release syndrome, hypotension, and acute respiratory distress syndrome (ARDS). Current infection control measures, including social distancing, wearing cloth masks, frequent cleaning and disinfecting of surfaces, frequent hand washing, and daily screening for COVID-19 symptoms are very important measures to reduce infections and severe health outcomes. Exposure to wildfire smoke may introduce additive or even multiplicative risk for SARS-CoV-2 infection and severity of disease in wildland firefighters. Thus, additional mitigative measures may be needed to prevent the co-occurrence of wildfire smoke exposure and SARS-CoV-2 infection.

Working in Smoke:: Wildfire Impacts on the Health of Firefighters and Outdoor Workers and Mitigation Strategies

Wildland firefighters work on wildfire incidents all over the United States and perform arduous work under extreme work conditions, including exposure to smoke. Wildland fire smoke is a mixture of hazardous air pollutants. For assessing wildland firefighter exposure to smoke, most studies measured carbon monoixde (CO) and particulate matter and reported changes in lung health by measured lung function, airway responsiveness, and respiratory symptoms across individual work shifts and single fire seasons. All fire personnel should understand the hazards of smoke and develop ways to mitigate exposure to smoke.

Characterization of occupational smoke exposure among wildland firefighters in the midwestern United States

Wildland firefighters are repeatedly exposed to elevated levels of wildland fire smoke (WFS) while protecting lives and properties from wildland fires. Studies reporting personal exposure concentrations of air pollutants in WFS during fire suppression or prescribed burn activities have been geographically limited to the western and southeastern United States. The objective of this study is to characterize exposure concentrations of air pollutants in WFS emissions among wildland firefighters who conducted prescribed burns in the Midwest. Between 2016 and 2019, a total of 35 firefighters (31 males and 4 females, age of 35.63 ± 9.31 years) were recruited to participate in this study. Personal particulate matter 2.5 (PM_2.5) and carbon monoxide (CO) exposure concentrations were measured during prescribed burns. The level of black carbon (BC) in WFS particulates was determined using the light transmission technique, while trace metal composition was analyzed using inductively coupled plasma mass spectrometry (ICP-MS). The results showed geometric means for PM_2.5, CO, and BC concentrations were 1.43 ± 0.13 mg/m³, 7.02 ± 0.69 ppm, and 58.79 ± 5.46 μg/m³, respectively. Although no occupational exposure limits (OELs) were exceeded by 8-h time-weighted average (TWA) exposure concentration observed in the firefighters, a total of 28 personal CO exposure concentrations were above the National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL) Ceiling (200 ppm) for CO. PM_2.5 and CO concentrations were about 2-7 times higher in the Midwest than the other regions. Firefighters who performed holding had higher CO exposure concentrations compared to firefighters who performed lighting (p < 0.01), while lighters were exposed to higher level of BC in the smoke particulates (p < 0.01), possibly due to the domination of exposure by different combustion sources and stages. The levels of trace metals in WFS particulates were well below the corresponding OELs and no task-related difference was observed except for manganese. Our results suggest that wildland firefighters in the midwestern region have higher WFS exposures while working at prescribed burns compared to those western and southeastern United States.

Characterization of exhaled breath condensate (EBC) non-exchangeable hydrogen functional types and lung function of wildland firefighters

Inhalation of smoke is shown to be associated with adverse respiratory outcomes in firefighters. Due to invasiveness of procedures to obtain airways lining fluid, the immediate responses of the target organ (i.e. lung) are secondarily assessed through biomarkers in blood and urine. The objective of this study was to identify changes in metabolic profile of exhaled breath condensate (EBC) and lung function of firefighters exposed to wildfires smoke. A total of 29 subjects were studied over 16 events; 14 of these subjects provided cross-shift EBC samples. The predominant types of non-exchangeable hydrogen in EBC were saturated oxygenated hydrogen, aliphatic alkyl and allylic. Non-exchangeable allylic and oxygenated hydrogen concentrations decreased in post-exposure EBC samples. Longer exposures were correlated with increased abundance of oxidized carbon in ketones, acids and esters. Post-exposure lung function declines (forced expiratory volume in 1 s (FEV₁): 0.08 l, forced vital capacity (FVC): 0.07 l, FEV₁/FVC: 0.03 l, peak expiratory flow (PEF): 0.39 l s^-1) indicated airways inflammation. They were related to exposure intensity (FEV₁ and FVC) and exposure duration (PEF). This study showed that EBC characterization of non-exchangeable hydrogen types by NMR may provide insights on EBC molecular compositions in response to smoke inhalation and facilitate targeted analysis to identify specific biomarkers.

Firefighters exposure to fire emissions: Impact on levels of biomarkers of exposure to polycyclic aromatic hydrocarbons and genotoxic/oxidative-effects

Firefighters represent one of the riskiest occupations, yet due to the logistic reasons, the respective exposure assessment is one of the most challenging. Thus, this work assessed the impact of firefighting activities on levels of urinary monohydroxyl-polycyclic aromatic hydrocarbons (OHPAHs; 1-hydroxynaphthalene, 1-hydroxyacenaphthene, 2-hydroxyfluorene, 1-hydroxyphenanthrene, 1-hydroxypyrene, 3-hydroxybenzo(a)pyrene) and genotoxic/oxidative-effect biomarkers (basal DNA and oxidative DNA damage) of firefighters from eight firehouses. Cardiac frequency, blood pressure and arterial oxygen saturation were also monitored. OHPAHs were determined by liquid-chromatography with fluorescence detection, while genotoxic/oxidative-effect biomarkers were assessed by the comet assay. Concentrations of total OHPAHs were up to 340% higher (p ≤ 0.05) in (non-smoking and smoking) exposed workers than in control subjects (non-smoking and non-exposed to combat activities); the highest increments were observed for 1-hydroxynaphthalene and 1-hydroxyacenaphthene (82-88% of ∑OHPAHs), and for 2-hydroxyfluorene (5-15%). Levels of biomarker for oxidative stress were increased in non-smoking exposed workers than in control group (316%; p ≤ 0.001); inconclusive results were found for DNA damage. Positive correlations were found between the cardiac frequency, ∑OHPAHs and the oxidative DNA damage of non-smoking (non-exposed and exposed) firefighters. Evidences were raised regarding the simultaneous use of these biomarkers for the surveillance of firefighters' health and to better estimate the potential short-term health risks.

Carbon monoxide exposures among U.S. wildland firefighters by work, fire, and environmental characteristics and conditions

Carbon monoxide (CO) exposure levels encountered by wildland firefighters (WLFs) throughout their work shift can change considerably within a few minutes due to the varied tasks that are performed and the changing environmental and fire conditions encountered throughout the day. In a U.S. Forest Service study during the 2009-2012 fire seasons, WLFs from 57 different fires across the U.S. were monitored for CO using CO data-logging detectors while an observer recorded worker tasks, fire characteristics, and environmental conditions at scheduled intervals. Exposures to CO for 735 WLF's work shifts were analyzed to assess the effect of variations among work tasks, fire characteristics, and environmental conditions. Geometric mean full shift time-weighted averages were low at 2.4 parts per million (ppm) and average length of work shift was 11 hr and 15 min. The task with the highest mean CO exposure was sawyer/swamper at 6.8 ppm; workers performing that task had an estimated 9 times higher odds of a having a 1-min CO measurement exceeding 25 ppm than the referent pump task (OR = 8.89, 95% CI = 1.97, 40.24). After adjusting CO exposure limits for shift length, elevation, and work level, 2% and 4% of the WLF's work shifts exceeded the National Institute for Occupational Safety and Health's recommended exposure level and the American Conference of Governmental Industrial Hygienist's threshold limit value, respectively. In regression modeling, variables that were significantly associated with elevated levels of CO exposure included: task, fuel model, wind orientation, crew type, relative humidity, type of attack, and wind speed. In the absence of instruments such as CO detectors that can determine and alert WLFs to elevated CO levels, recognition of the conditions that lead to elevated levels of CO exposure can assist WLFs to effectively use administrative controls, such as work rotations, to minimize exposures.

Incident command post exposure to polycyclic aromatic hydrocarbons and particulate matter during a wildfire

Wildland firefighters engaged in fire suppression activities are often exposed to hazardous air pollutants such as polycyclic aromatic hydrocarbons (PAHs) and particulate matter (PM_2.5) during wildfires with no respiratory protection. Although the most significant exposures to smoke likely occur on the fireline, wildland firefighters may also be exposed at the incident command post (ICP), an area designated for wildfire suppression support operations. Our objective was to characterize exposures of PAHs and PM_2.5 near an ICP during a wildfire event in California. We collected area air samples for PAHs and PM_2.5, during the first 12 days of a wildfire event. PAH area air samples were actively collected in 12-hr shifts (day and night) using XAD4-coated quartz fiber filters and XAD2 sorbent tubes and analyzed for 17 individual PAHs. Hourly area PM_2.5 concentrations were measured with an Environmental Beta Attenuation Monitor. Most PAH concentrations generally had similar concentrations during the day and night. PM_2.5 concentrations were higher during the day, due to increased fire activity, than at night. The highest concentrations of the 17 PAHs measured were for naphthalene, phenanthrene, and retene. The location of an ICP may be a critical factor in reducing these potential exposures to firefighters during wildfire events. Additionally, exposures could be reduced by utilizing clean air tents or sleeping trailers with HEPA filtration or setting up smaller camps in less smokey areas closer to the fireline for firefighters. Although measured exposures to PAHs for firefighters from smoke are lower at an ICP, these exposures still contribute to the overall cumulative work exposures.

Smoldering and flaming biomass wood smoke inhibit respiratory responses in mice

Background: Acute and chronic exposures to biomass wildfire smoke pose significant health risks to firefighters and impacted communities. Susceptible populations such as asthmatics may be particularly sensitive to wildfire effects. We examined pulmonary responses to biomass smoke generated from combustion of peat, oak, or eucalyptus in control and house dust mite (HDM)-allergic mice. Methods: Mice were exposed 1 h/d for 2 consecutive days to emissions from each fuel type under smoldering or flaming conditions (∼40 or ∼3.3 mg PM/m³, respectively) while maintaining comparable CO levels (∼60-120 ppm). Results: Control and allergic mice reduced breathing frequency during exposure to all biomass emissions compared with pre-exposure to clean air. Smoldering eucalyptus and oak, but not peat, further reduced frequency compared to flaming conditions in control and allergic groups, while also reducing minute volume and peak inspiratory flow in control mice. Several biochemical and cellular markers of lung injury and inflammation were suppressed by all biomass emission types in both HDM-allergic and control mice. Control mice exposed to flaming eucalyptus at different PM concentrations (C) and times (T) with the same C × T product had a greater decrease in breathing frequency with high concentration acute exposure compared with lower concentration episodic exposure. This decrease was ameliorated by PM HEPA filtration, indicating that the respiratory changes were partially mediated by biomass smoke particles. Conclusion: These data show that exposure to smoldering eucalyptus or oak smoke inhibits respiratory responses to a greater degree than peat smoke. Anti-inflammatory effects of CO may possibly contribute to smoke-induced suppression of allergic inflammatory responses.

Wildland firefighter smoke exposure and risk of lung cancer and cardiovascular disease mortality

Wildland firefighters are exposed to wood smoke, which contains hazardous air pollutants, by suppressing thousands of wildfires across the U. S. each year. We estimated the relative risk of lung cancer and cardiovascular disease mortality from existing PM_2.5 exposure-response relationships using measured PM₄ concentrations from smoke and breathing rates from wildland firefighter field studies across different exposure scenarios. To estimate the relative risk of lung cancer (LC) and cardiovascular disease (CVD) mortality from exposure to PM_2.5 from smoke, we used an existing exposure-response (ER) relationship. We estimated the daily dose of wildfire smoke PM_2.5 from measured concentrations of PM₄, estimated wildland firefighter breathing rates, daily shift duration (hours per day) and frequency of exposure (fire days per year and career duration). Firefighters who worked 49 days per year were exposed to a daily dose of PM₄ that ranged from 0.15 mg to 0.74 mg for a 5- and 25-year career, respectively. The daily dose for firefighters working 98 days per year of PM₄ ranged from 0.30 mg to 1.49 mg. Across all exposure scenarios (49 and 98 fire days per year) and career durations (5-25 years), we estimated that wildland firefighters were at an increased risk of LC (8 percent to 43 percent) and CVD (16 percent to 30 percent) mortality. This unique approach assessed long term health risks for wildland firefighters and demonstrated that wildland firefighters have an increased risk of lung cancer and cardiovascular disease mortality.

Risk of asthma and chronic obstructive pulmonary disease in a large historical cohort of Danish firefighters

OBJECTIVE

Firefighters are exposed to numerous respiratory hazards, but large studies on the risk of pulmonary disease are scarce. The objective of this study was to examine incidence of asthma and chronic obstructive pulmonary disease (COPD) in a nationwide cohort of Danish firefighters.

METHODS

We used individual historical employment records on 11 968 Danish male firefighters primarily supplied by trade unions and fire agencies. Furthermore, we used the Supplementary Pension Fund Register to form an occupational reference group consisting of military employees. Information on respiratory incidence was retrieved from the nationwide Danish National Patient Registry. Age and calendar time standardised incidence ratio (SIR) and Poisson regression analyses (incidence rate ratio) were used for estimation of risks, including 95% CIs.

RESULTS

Compared with military employees, the overall age and calendar-time adjusted risk for asthma was significantly increased among full-time firefighters (SIR=1.58, 95% CI 1.32 to 1.88), but not among part-time/volunteer firefighters. Full-time firefighters' risk for asthma did not vary by duration of employment. No consistent evidence of an increased risk for chronic obstructive pulmonary disease was detected.

CONCLUSION

Danish firefighters have an increased risk of asthma, but the causes, whether occupational or not, remain to be established.

The long-term rate of change in lung function in urban professional firefighters: a systematic review

BACKGROUND

Despite the known occupational hazards, it is not yet clear whether long-term career firefighting leads to a greater rate of decline in lung function than would normally be expected, and how this rate of change is affected by firefighting exposures and other risk/protective factors.

METHODS

A systematic search of online electronic databases was conducted to identify longitudinal studies reporting on the rate of change in the forced expiratory volume in one second (FEV1) of forced vital capacity (FVC). Included studies were critically appraised to determine their risk of bias using the Research Triangle Institute Item Bank (RTI-IB) on Risk of Bias and Precision of Observational Studies.

RESULTS

Twenty-two studies were identified for inclusion, from four different countries, published between 1974 and 2016. Examined separately, studies were categorised by the type of firefighting exposure. Firefighters experienced variable rates of decline in lung function, which were particularly influenced by cigarette smoking. The influence of routine firefighting exposures is unclear and limited by the methods of measurement, while firefighters exposed to 'non-routine' severe exposures unanimously experienced accelerated declines.

CONCLUSIONS

The data provided by longitudinal studies provide an unclear picture of how the rate of change in lung function of firefighters relates to routine exposures and how it compares to the rate of change expected in a working-age population. Non-smoking firefighters who routinely wear respiratory protection are more likely than otherwise to have a normal rate of decline in lung function. Exposure to catastrophic events significantly increases the rate of decline in firefighter lung function but there is limited evidence detailing the effect of routine firefighting. Future studies will benefit from more robust methods of measuring exposure.

TRIAL REGISTRATION

International Prospective Register of Systematic Reviews (PROSPERO), registration number ( CRD42017058499 ).

Elevated Exposures to Polycyclic Aromatic Hydrocarbons and Other Organic Mutagens in Ottawa Firefighters Participating in Emergency, On-Shift Fire Suppression

Occupational exposures to combustion emissions were examined in Ottawa Fire Service (OFS) firefighters. Paired urine and dermal wipe samples (i.e., pre- and post-event) as well as personal air samples and fire event questionnaires were collected from 27 male OFS firefighters. A total of 18 OFS office workers were used as additional controls. Exposures to polycyclic aromatic hydrocarbons (PAHs) and other organic mutagens were assessed by quantification of urinary PAH metabolite levels, levels of PAHs in dermal wipes and personal air samples, and urinary mutagenicity using the Salmonella mutagenicity assay (Ames test). Urinary Clara Cell 16 (CC16) and 15-isoprostane F_2t (8-iso-PGF_2α) levels were used to assess lung injury and overall oxidative stress, respectively. The results showed significant 2.9- to 5.3-fold increases in average post-event levels of urinary PAH metabolites, depending on the PAH metabolite (p < 0.0001). Average post-event levels of urinary mutagenicity showed a significant, event-related 4.3-fold increase (p < 0.0001). Urinary CC16 and 8-iso-PGF_2α did not increase. PAH concentrations in personal air and on skin accounted for 54% of the variation in fold changes of urinary PAH metabolites (p < 0.002). The results indicate that emergency, on-shift fire suppression is associated with significantly elevated exposures to combustion emissions.

Bronchial wheezing predicts inflammation and respiratory failure in fire smoke victims

BACKGROUND

Acute fire smoke inhalation injury involves inflammatory mediators whose roles are poorly understood. We carried out a prospective observational study of fire smoke victims to identify clinical and biochemical markers that may predict pulmonary dysfunction and investigated possible correlations between dysfunction and cytokines in bronchoalveolar lavage (BAL) fluid and blood.

METHODS

Forty patients with respiratory and/or neurological symptoms following acute fire smoke inhalation had pulmonary function tests and blood gas analyses performed on admission, at discharge, and after 3 months. Cytokines were measured using BioPlex/XMap technology.

RESULTS

On admission, 30 (75%) patients had dyspnea. Patients presenting with bronchial wheezing (n = 14) had significantly lower PEF (201 l/min, 82-360) than non-wheezing patients (406 l/min, 100-683) (n = 16, P = 0.03). Bronchial wheezing predicted need for ICU treatment with OR = 93.3 at 95% CI (P < 0.001) and was associated with gas exchange impairment, with mean p_a O₂ /FiO₂ ratio 34.4 (11.8-49.8) kPa on admission and 21.3 (8.3-44.5) kPa 48 h later. Blood HbCO also predicted ICU treatment, with OR = 1.58 at 95% CI (P < 0.001). Serum CRP, IL-6, IL-8, and MCP-1 were significantly higher in wheezing patients after 12-24 h compared with non-wheezing patients and study controls. Cytokine levels were still elevated after 3 months. BAL fluid had significantly higher levels of IL-8, MCP-1, IL-1β, and G-CSF compared with healthy controls.

CONCLUSION

In victims of fire smoke inhalation, pulmonary wheezing predicts inflammation, pulmonary dysfunction, respiratory failure, and need for intensive care.

Occupational exposure of firefighters to polycyclic aromatic hydrocarbons in non-fire work environments

This work aims to characterize personal exposure of firefighters to polycyclic aromatic hydrocarbons (PAHs) in non-fire work environments (fire stations), and assesses the respective risks. Eighteen PAHs (16 considered by USEPA as priority pollutants, dibenzo[a,l]pyrene and benzo[j]fluoranthene) were monitored in breathing zones of workers at five Portuguese fire stations during a normal shift. The obtained levels of PAHs fulfilled all existent occupational exposure limits as well as air quality guidelines with total concentrations (ΣPAHs) in range of 46.8-155ngm^-3. Light compounds (2-3 rings) were the most predominant congeners (74-96% of ΣPAHs) whereas PAHs with 5-6 rings accounted 3-9% of ΣPAHs. Fuel and biomass combustions, vehicular traffic emissions, and use of lubricant oils were identified as the main sources of PAHs exposure at the studied fire corporations. Incremental lifetime cancer risks were below the recommend USEPA guideline of 10^-6 and thus negligible for all the studied subjects, but WHO health-based guideline level of 10^-5 was exceeded (9-44 times) at all fire corporations. These results thus show that even during non-fire situations firefighters are exposed to PAHs at levels that may promote some adverse health outcomes; therefore the respective occupational exposures to these compounds should be carefully controlled.

Individual and cumulative impacts of fire emissions and tobacco consumption on wildland firefighters' total exposure to polycyclic aromatic hydrocarbons

There is limited information about wildland firefighters' exposure to polycyclic aromatic hydrocarbons (PAHs), being scarce studies that included the impact of tobacco consumption. Thus, this work evaluated the individual and cumulative impacts of firefighting activities and smoking on wildland firefighters' total exposure to PAHs. Six urinary PAH metabolites (1-hydroxynaphthalene (1OHNaph), 1-hydroxyacenaphthene (1OHAce), 2-hydroxyfluorene (2OHFlu), 1-hydroxyphenanthrene (1OHPhen), 1-hydroxypyrene (1OHPy), and 3-hydroxybenzo[a]pyrene (3OHB[a]P)) were quantified by high-performance liquid chromatography with fluorescence detection. Firefighters from three fire stations were characterized and organized in three groups: non-smoking and non-exposed to fire emissions (NSNExp), smoking non-exposed (SNExp), and smoking exposed (SExp) individuals. 1OHNaph+1OHAce were the most predominant OH-PAHs (66-91% ∑OH-PAHs), followed by 2OHFlu (2.8-28%), 1OHPhen (1.3-7%), and 1OHPy (1.4-6%). 3OHB[a]P, the carcinogenicity PAH biomarker, was not detected. Regular consumption of tobacco increased 76-412% ∑OH-PAHs. Fire combat activities promoted significant increments of 158-551% ∑OH-PAHs. 2OHFlu was the most affected compound by firefighting activities (111-1068%), while 1OHNaph+1OHAce presented the more pronounced increments due to tobacco consumption (22-339%); 1OHPhen (76-176%) and 1OHPy (20-220%) were the least influenced ones. OH-PAH levels of SExp firefighters were significantly higher than in other groups, suggesting that these subjects may be more vulnerable to develop and/or aggravate diseases related with PAHs exposure.

Occupational Exposure to Polycyclic Aromatic Hydrocarbon of Wildland Firefighters at Prescribed and Wildland Fires

Wildland firefighters suppressing wildland fires or conducting prescribed fires work long shifts during which they are exposed to high levels of wood smoke with no respiratory protection. Polycyclic aromatic hydrocarbons (PAHs) are hazardous air pollutants formed during incomplete combustion. Exposure to PAHs was measured for 21 wildland firefighters suppressing two wildland fires and 4 wildland firefighters conducting prescribed burns in California. Personal air samples were actively collected using XAD4-coated quartz fiber filters and XAD2 sorbent tubes. Samples were analyzed for 17 individual PAHs through extraction with dichloromethane and gas chromatograph-mass spectrometer analysis. Naphthalene, retene, and phenanthrene were consistently the highest measured PAHs. PAH concentrations were higher at wildland fires compared to prescribed fires and were highest for firefighters during job tasks that involve the most direct contact with smoke near an actively burning wildland fire. Although concentrations did not exceed current occupational exposure limits, wildland firefighters are exposed to PAHs not only on the fire line at wildland fires, but also while working prescribed burns and while off-duty. Characterization of occupational exposures from wildland firefighting is important to understand better any potential long-term health effects.

Wildland firefighter deaths in the United States: A comparison of existing surveillance systems

Wildland fire fighting is a high-risk occupation requiring considerable physical and psychological demands. Multiple agencies publish fatality summaries for wildland firefighters; however, the reported number and types vary. At least five different surveillance systems capture deaths, each with varying case definitions and case inclusion/exclusion criteria. Four are population-level systems and one is case-based. System differences create challenges to accurately characterize fatalities. Data within each of the five surveillance systems were examined to better understand the types of wildland firefighter data collected, to assess each system's utility in characterizing wildland firefighter fatalities, and to determine each system's potential to inform prevention strategies. To describe similarities and differences in how data were recorded and characterized, wildland fire deaths for three of the population-based systems were matched and individual fatalities across systems were compared. Between 2001 and 2012, 247 unique deaths were captured among the systems; 73% of these were captured in all three systems. Most common causes of death in all systems were associated with aviation, vehicles, medical events, and entrapments/burnovers. The data show that, although the three systems often report similar annual summary statistics, events captured in each system vary each year depending on the types of events that the system is designed to track, such as inclusion/exclusion of fatalities associated with the Hometown Heroes Survivor Benefits Act of 2003. The overarching and central goal of each system is to collect accurate and timely information to improve wildland firefighter safety and health. Each system is unique and has varying inclusion and exclusion criteria for capturing and tracking different subsets of wildland firefighter tasks and duties. Use of a common case definition and better descriptions and interpretations of the data and the results would help to more accurately characterize wildland firefighter traumatic injuries and illnesses, lessen the likelihood for misinterpretation of wildland firefighter fatality data, and assist with defining the true occupational injury burden within this high-risk population.

Polycyclic aromatic hydrocarbons at fire stations: firefighters' exposure monitoring and biomonitoring, and assessment of the contribution to total internal dose

This work characterizes levels of eighteen polycyclic aromatic hydrocarbons (PAHs) in the breathing air zone of firefighters during their regular work shift at eight Portuguese fire stations, and the firefighters' total internal dose by six urinary monohydroxyl metabolites (OH-PAHs). Total PAHs (ΣPAHs) concentrations varied widely (46.4-428ng/m³), mainly due to site specificity (urban/rural) and characteristics (age and layout) of buildings. Airborne PAHs with 2-3 rings were the most abundant (63.9-95.7% ΣPAHs). Similarly, urinary 1-hydroxynaphthalene and 1-hydroxyacenaphthene were the predominant metabolites (66-96% ΣOH-PAHs). Naphthalene contributed the most to carcinogenic ΣPAHs (39.4-78.1%) in majority of firehouses; benzo[a]pyrene, the marker of carcinogenic PAHs, accounted with 1.5-10%. Statistically positive significant correlations (r≥0.733, p≤0.025) were observed between ΣPAHs and urinary ΣOH-PAHs for firefighters of four fire stations suggesting that, at these sites, indoor air was their major exposure source of PAHs. Firefighter's personal exposure to PAHs at Portuguese fire stations were well below the existent occupational exposure limits. Also, the quantified concentrations of post-shift urinary 1-hydroxypyrene in all firefighters were clearly lower than the benchmark level (0.5μmol/mol) recommended by the American Conference of Governmental Industrial Hygienists.

A cross-sectional survey of occupational history as a wildland firefighter and health

BACKGROUND

Little is known regarding the impact of long-term wildland firefighting on health. Our objective was to investigate associations between duration of wildland firefighting experience and the prevalence of self-reported health outcomes.

METHODS

We ascertained employment, health, and demographic information on 499 current wildland firefighters (WLFFs) via questionnaire.

RESULTS

Relative to those with less than 10 years of experience as a WLFF, those with 10-19 years of experience had significantly greater odds of having ever been diagnosed with hypertension, as did those with 20 or more years of experience. Significant associations were observed for report of physician-diagnosed heart arrhythmia and previous knee surgery.

CONCLUSIONS

We observed significant links between a greater number of years as a WLFF and self-report of two subclinical cardiovascular risk factors as well as markers of musculoskeletal health. Additional studies are needed to determine if findings can be generalized to all WLFFs.

Health effects of carbon-containing particulate matter: focus on sources and recent research program results

Air pollution is a complex mixture of gas-, vapor-, and particulate-phase materials comprised of inorganic and organic species. Many of these components have been associated with adverse health effects in epidemiological and toxicological studies, including a broad spectrum of carbonaceous atmospheric components. This paper reviews recent literature on the health impacts of organic aerosols, with a focus on specific sources of organic material; it is not intended to be a comprehensive review of all the available literature. Specific emission sources reviewed include engine emissions, wood/biomass combustion emissions, biogenic emissions and secondary organic aerosol (SOA), resuspended road dust, tire and brake wear, and cooking emissions. In addition, recent findings from large toxicological and epidemiological research programs are reviewed in the context of organic PM, including SPHERES, NPACT, NERC, ACES, and TERESA. A review of the extant literature suggests that there are clear health impacts from emissions containing carbon-containing PM, but difficulty remains in apportioning responses to certain groupings of carbonaceous materials, such as organic and elemental carbon, condensed and gas phases, and primary and secondary material. More focused epidemiological and toxicological studies, including increased characterization of organic materials, would increase understanding of this issue.

Arterial stiffness, oxidative stress, and smoke exposure in wildland firefighters

OBJECTIVES

To assess the association between exposure, oxidative stress, symptoms, and cardiorespiratory function in wildland firefighters.

METHODS

We studied two Interagency Hotshot Crews with questionnaires, pulse wave analysis for arterial stiffness, spirometry, urinary 8-iso-prostaglandin F2α (8-isoprostane) and 8-hydroxy-2'-deoxyguanosine (8-OHdG), and the smoke exposure marker (urinary levoglucosan). Arterial stiffness was assessed by examining levels of the aortic augmentation index, expressed as a percentage. An oxidative stress score comprising the average of z-scores created for 8-OHdG and 8-isoprostane was calculated.

RESULTS

Mean augmentation index % was higher for participants with higher oxidative stress scores after adjusting for smoking status. Specifically for every one unit increase in oxidative stress score the augmentation index % increased 10.5% (95% CI: 2.5, 18.5%). Higher mean lower respiratory symptom score was associated with lower percent predicted forced expiratory volume in one second/forced vital capacity.

CONCLUSIONS

Biomarkers of oxidative stress may serve as indicators of arterial stiffness in wildland firefighters.