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

Longitudinal changes in lung function following post-9/11 military deployment in symptomatic veterans

RATIONALE

Exposure to burn pit smoke, desert and combat dust, and diesel exhaust during military deployment to Southwest Asia and Afghanistan (SWA) can cause deployment-related respiratory diseases (DRRDs) and may confer risk for worsening lung function after return.

METHODS

Study subjects were SWA-deployed veterans who underwent occupational lung disease evaluation (n = 219). We assessed differences in lung function by deployment exposures and DRRD diagnoses. We used linear mixed models to assess changes in lung function over time.

RESULTS

Most symptomatic veterans reported high intensity deployment exposure to diesel exhaust and burn pit particulates but had normal post-deployment spirometry. The most common DRRDs were deployment-related distal lung disease involving small airways (DDLD, 41%), deployment-related asthma (DRA, 13%), or both DRA/DDLD (24%). Those with both DDLD/DRA had the lowest estimated mean spirometry measurements five years following first deployment. Among those with DDLD alone, spirometry measurements declined annually, adjusting for age, sex, height, weight, family history of lung disease, and smoking. In this group, the forced expiratory volume in the first second/forced vital capacity (FEV1/FVC) ratio declined 0.2% per year. Those with more intense inhalational exposure had more abnormal lung function. We found significantly lower estimated FVC and total lung capacity five years following deployment among active duty participants (n = 173) compared to those in the reserves (n = 26).

CONCLUSIONS

More intense inhalational exposures were linked with lower post-deployment lung function. Those with distal lung disease (DDLD) experienced significant longitudinal decline in FEV1/FVC ratio, but other DRRD diagnosis groups did not.

The status and influencing factors of lung ventilation function in employees exposed to dust in enterprises of the XPCC, China

Background

Occupational health is closely related to harmful factors in the workplace. Dust is the primary contributing factor causing impaired lung ventilation function among employees with dust exposure, and their lung ventilation function may also be influenced by other factors. We aimed at assessing the status and influencing factors of lung ventilation function among employees exposed to dust in the enterprises of the Eighth Division located in the Xinjiang Production and Construction Corps (XPCC), China.

Methods

Employees exposed to dust in enterprises of the Eighth Division located in the XPCC in 2023 were selected as the subjects of this cross-sectional study. Their lung ventilation function indicators were extracted from health examination records, and an on-site electronic questionnaire survey was conducted among them. Binary logistic regression analyses were conducted to evaluate the factors influencing lung ventilation function.

Results

According to the fixed value criteria, the abnormal rates of forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and FEV1/FVC were 31.6, 1.4, and 0.4%, respectively. The lower limit of normal (LLN) criteria could overestimate the rate of abnormal lung ventilation function. Several factors were related to impaired lung ventilation function, including gender, age, education level, marital status, body mass index (BMI), smoking status, physical activity, the type of dust, industry, enterprise scale, occupation, length of service, working shift, monthly income, and respiratory protection.

Conclusions

A relatively low abnormal rate of lung ventilation function was observed among employees exposed to dust in enterprises of the Eighth Division, XPCC, and their lung ventilation function was associated with various factors. Effective measures should be taken urgently to reduce the effects of adverse factors on lung ventilation function, thereby further protecting the health of the occupational population.

Association of firefighting exposures with lung function using a novel job exposure matrix (JEM)

OBJECTIVES

Characterisation of firefighters' exposures to dangerous chemicals in smoke from non-wildfire incidents, directly through personal monitoring and indirectly from work-related records, is scarce. The aim of this study was to evaluate the association between smoke particle exposures (P) and pulmonary function.

METHODS

The study period spanned from January 2010 through September 2021. Routine firefighting P were estimated using fire incident characteristics, response data and emission factors from a novel job exposure matrix. Linear mixed effects modelling was employed to estimate changes in pulmonary function as measured by forced expiratory volume in one second (FEV1). Models controlled for age, race/ethnicity, height, smoking and weight.

RESULTS

Every 1000 kg P was associated with 13 mL lower FEV1 (β=-13.34; 95% CI=-13.98 to -12.70) over the entire 12-year follow-up period. When analysing exposures within 3 months before PFT measurements, 1000 kg P was associated with 27 mL lower FEV1 (β=-26.87; 95% CI=-34.54 to -19.20). When evaluating P estimated within 3 months of a pulmonary function test (PFT), stronger associations were observed among those most highly exposed to the World Trade Center (WTC) disaster (β=-12.90; 95% CI=-22.70 to -2.89); the association of cumulative exposures was similar for both highly and less highly exposed individuals.

DISCUSSION

Smoke particle exposures were observed to have modest short-term and long-term associations with pulmonary function, particularly in those who, previously, had high levels of WTC exposure. Future work examining the association between P and pulmonary function among non-WTC exposed firefighters will be essential for disentangling the effects of ageing, routine firefighting and WTC exposures.

Perceptions of lung function surveillance in urban firefighters

BACKGROUND AND OBJECTIVE

Workplace health and safety (WHS) is an important responsibility falling on both employers and employees and is most effective when the perspectives of all stakeholders are considered. This study aimed to explore the facilitators and barriers to a voluntary workplace lung function surveillance program from the perspective of urban firefighters and describe their perceptions of its value.

METHODS

Using a qualitative, descriptive methodology, firefighters who had participated in a longitudinal lung function surveillance study were invited to participate in semi-structured interviews. Purposeful, maximum variation sampling was used to achieve diversity in those firefighters invited to participate. We used inductive content analysis to identify themes.

RESULTS

Interviews with 15 firefighters identified 3 main themes: (i) practical experience of surveillance (administration, communication, workplace culture change, convenience, acceptability, and appeal); (ii) value of surveillance (lung health efficacy and control, social support, workplace management support/motivations, contribution to global firefighter health); and (iii) contribution of surveillance to health (occupational risk, relevance in the context of total health, workability, and fitness and future value).

CONCLUSION

Practical and psychosocial facilitators and barriers to providing lung function surveillance in the fire service were identified. In addition to the personal benefits of detecting adverse lung health and allowing for medical intervention, factors known to positively influence firefighter workplace wellbeing, such as providing peace of mind, feedback on good work practices, motivation to utilize control measures, management commitment to health, and providing data to assist with global knowledge were valued aspects of longitudinal lung function surveillance.

An examination of psychometric properties of study quality assessment scales in meta-analysis: Rasch measurement model applied to the firefighter cancer literature

Most existing quality scales have been developed with minimal attention to accepted standards of psychometric properties. Even for those that have been used widely in medical research, limited evidence exists supporting their psychometric properties. The focus of our current study is to address this gap by evaluating the psychometrics properties of two existing quality scales that are frequently used in cancer observational research: (1) Item Bank on Risk of Bias and Precision of Observational Studies developed by the Research Triangle Institute (RTI) International and (2) Newcastle-Ottawa Quality Assessment Scale (NOQAS). We used the Rasch measurement model to evaluate the psychometric properties of two quality scales based on the ratings of 49 studies that examine firefighters' cancer incidence and mortality. Our study found that RTI and NOQAS have an acceptable item reliability. Two raters were consistent in their assessment, demonstrating high interrater reliability. We also found that NOQAS has more items that show better fit than the RTI scale. The NOQAS produced lower study quality scores with a smaller variation, suggesting that NOQAS items are much easier to rate. Our findings accord with a previous study, which conclude that the RTI scale was harder to apply and thus produces more heterogenous quality scores than NOQAS. Although both RTI and NOQAS showed high item reliability, NOQAS items are better fit to the underlying construct, showing higher validity of internal structure and stronger psychometric properties. The current study adds to our understanding of the psychometric properties of NOQAS and RTI scales for future meta-analyses of observational studies, particularly in the firefighter cancer literature.

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.

Development of a job-exposure matrix (JEM) for exposure to smoke particle mass among firefighters of the Fire Department of the City of New York (FDNY)

OBJECTIVES

A refined job exposure matrix (JEM) based on incident types and severities and response characteristics was developed for firefighters to estimate quantities of smoke particles emitted during structural and non-structural fire incidents from 2010 to 2021.

METHODS

The cohort included a subset of 3237 Fire Department of the City of New York firefighters who responded to at least one incident between 2010 and 2021, prior to retirement. Fire incident data included dates, type, severity (alarm level) and location. Response data included dates worked, firehouse, position titles and shift lengths for each firefighter. The quantity of smoke particle mass generated during structural and non-structural fires adjusted by individual firefighter engagement was computed using the United States Environmental Protection Agency AP-42 emissions framework. Correlations between years of employment, fire responses and career total particle mass concentration by firefighter were examined. Linear regression models were fit and corresponding R² values were calculated.

RESULTS

Firefighters responded to a median of 424.7 (IQR=202.3-620.0) annual incidents/person; 17.6% were fire incidents (median=77.1; IQR=40.4-114.0). Structural fires were the most common type of fire incident (72.5% of annual incidents/person; median=55.9; IQR=29.6-85.5). Incident severity (alarm level) and firefighter engagement (position title) appeared to differentiate between high and low exposure regimes (R²=0.43). Incident severity explained most of the variability of particle exposures (R²=0.90).

CONCLUSIONS

Using the JEM, job-related smoke particle concentrations were estimated to vary by incident type, incident severity and firefighter engagement, highlighting the importance of using refined measures, so that future studies can more accurately evaluate associations between firefighting and health outcomes.

Comparison of the risks of occupational diseases, avoidable hospitalization, and all-cause deaths between firefighters and non-firefighters: A cohort study using national health insurance claims data

Objectives

National Health Insurance claims data were used to compare the incidence of occupational diseases, avoidable hospitalization, and all-cause death standardized incidence ratio and hazard ratio between firefighters and non-firefighters.

Methods

The observation period of the study was from 2006 to 2015 and a control group (general workers and national and regional government officers/public educational officers) and a firefighter group was established. The dependent variables were occupational diseases, avoidable hospitalization (AH), and all-cause death. The analysis was conducted in three stages. First, the standardized incidence ratios were calculated using the indirect standardization method to compare the prevalence of the disease between the groups (firefighter and non-firefighter groups). Second, propensity score matching was performed for each disease in the control group. Third, the Cox proportional hazards model was applied by matching the participants.

Results

The standardized incidence ratio and Cox regression analyses revealed higher rates of noise-induced hearing loss, ischemic heart disease, asthma, chronic obstructive pulmonary disease, cancer, back pain, admission due to injury, mental illness, depression, and AH for firefighters than general workers. Similarly, the rates of noise-induced hearing loss, ischemic heart disease, asthma, chronic obstructive pulmonary disease, back pain, admission due to injury, mental illness, depression, and AH were higher in the firefighter group than in the national and regional government officer/public educational officer group.

Conclusions

The standardized incidence ratios and hazard ratios for most diseases were high for firefighters. Therefore, besides the prevention and management of diseases from a preventive medical perspective, management programs, including social support and social prescriptions in the health aspect, are needed.

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.

Longitudinal Changes in Spirometry in Deployed Air Force Firefighters

INTRODUCTION

Inhalational exposures are common among service members who deploy to southwest Asia. The objective of this study is to determine if deployed Air Force firefighters have any decline in spirometry related to deployment.

METHODS

This study is a retrospective chart review.

RESULTS

The database search identified 302 firefighters with documentation of two separate spirometry examinations. For deployed firefighters, mean change in forced expiratory volume at 1 second (FEV1) percent predicted was -1.01 ± 7.86, forced vital capacity (FVC) was -0.46 ± 10.26 predicted, and mid-expiratory flow (FEF25-75) was -0.13 ± 12.97. For firefighters who had never deployed, mean change in FEV1 percent predicted was +0.08 ± 7.09, FVC was +0.72 ± 7.75, and FEF25-75 was -0.66 ± 16.17.

CONCLUSION

There does not appear to be evidence that deployment causes a significant change in lung function as measured by spirometry.

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.

Assessment and outcomes of firefighter applicants with possible asthma

BACKGROUND

Firefighter applicants (FFAs) with a history of asthma may be refused entry to the fire service because of potentially putting themselves and others at risk.

AIMS

We undertook a service evaluation to identify respiratory and employment outcomes of FFAs with a history of asthma who had undergone additional respiratory assessment at our specialist occupational lung disease clinic during 2005-19.

METHODS

We reviewed FFA medical records and categorized them as having either no current asthma or definite/probable asthma at the time of clinic assessment. 'No current asthma' was defined as negative non-specific bronchial hyper-responsiveness (BHR) to histamine/methacholine, and no symptoms or treatment within the 2 years before clinic. 'Definite/probable current asthma' was defined as either positive BHR, or negative BHR with symptoms and/or treatment within the previous 2 years. Around 1 year later, we contacted FFAs to enquire about their application outcome and current respiratory symptoms.

RESULTS

Data were available on 116 applicants; of whom, 45% (n = 52) had definite/probable current asthma and were significantly more likely to be older, atopic to common aeroallergens, report atopic disease and have a lower forced expiratory volume in one second/forced vital capacity ratio compared with applicants with no current asthma. Only two individuals' applications were rejected due to asthma. At follow-up, just 2 (2%) of the 90 operational firefighters reported any recent trouble with asthma.

CONCLUSIONS

A history of asthma alone is not sufficient to determine current asthma in FFAs. Even with a diagnosis of current asthma, FFAs are mostly successful in their application to join the fire service.

The Health of Firefighters Deployed to the Fort McMurray Fire: Lessons Learnt

Introduction: Firefighters were working in exceptionally difficult conditions during the Fort McMurray/Horse River fire in May 2016. Methods: From mid-May, we recruited firefighters from 13 fire services as they returned from the fire. In October 2016 we extended recruitment to all Alberta-based firefighters deployed to the fire. In December 2017-May 2018 we sent a first online follow-up: this concentrated on mental health supports. The second follow-up, in October 2018-January 2019, included screening scales for respiratory ill-health and PTSD. All three contacts included visual analogue scales for chest symptoms and the Hospital Anxiety and Depression Scale. We estimated exposure to PM2.5, and calculated an exposure mitigation index from reports of respiratory protective equipment (RPE). Results: We recruited 1,234 firefighters and examined the relation of respiratory symptoms to estimated particulate exposure. The relation was strong immediately post fire but weakened over time. We found less chest tightness and cough in those whose RPE in the first week mitigated exposure by at least 10%. We examined the relation between particulate exposure and mental ill-health from screening questionnaires and found those with high exposure (reflecting the ferocity of the fire) had poorer mental health scores. Firefighters reporting their "worst moment during the fire" was life threatening were more anxious at second follow-up. Overall both anxiety and depression scores increased at successive contacts, more so in those with mental ill-health recorded in physician billing records before the fire. Discussion: The results from this study overall suggest on-going fire-related health effects in a substantial minority of firefighters, similar to those reported in the longitudinal follow-up of firefighters after the collapse of the World Trade Centre. Self-reports of both respiratory symptoms and mental ill-health were strongly related, soon after the fire, to estimated particulate exposures. Anxiety increased over time since the fire in those who felt their life or safety had been threatened, underlining the need for ongoing support. Our conclusions about the benefits of rapid research relate particularly to the collection of biomarkers of exposure as quickly and widely as possible, and the establishment of a nominal list of participants before they are too widely dispersed.

Respiratory Outcomes of Firefighter Exposures in the Fort McMurray Fire: A Cohort Study From Alberta Canada

OBJECTIVE

Determine effects on respiratory health of firefighters attending a catastrophic wildfire.

METHODS

Within the Alberta Administrative Health Database, we identified five community-based controls for each firefighter in a cohort of 1234 deployed to the 2016 Fort McMurray fire. Spirometry records were identified and a stratified sample assessed clinically. We estimated PM2.5 particles exposure.

RESULTS

Firefighters had an increased risk of asthma consultation post-fire (OR new onset asthma = 2.56; 95%CI 1.75 to 3.74). Spirometry showed decreased FEV1 and FVC with increasing exposure. In the clinical assessment, 20% had a positive MCT and 21% BWT. Those with ongoing fire-related symptoms had a higher concurrence of positive MCT and BWT (OR = 4.35; 95%CI 1.11 to 17.12). Lower diffusion capacity related to higher exposure.

CONCLUSIONS

Massive exposures during a wildfire are associated with non-resolving airways damage.

Decreased Pulmonary Function Over 5 Years in US Firefighters

To examine changes in pulmonary function over a 5-year period in US firefighters.

Health consequences of thick forest fire smoke to healthy residents in Riau, Indonesia: a cross-sectional study

BACKGROUND Indonesia forest fire in 2015 emitted a huge amount of pollutants into the air. This study was aimed to assess the health consequences of forest fire smoke in healthy residents in Riau during forest fire disaster in 2015. METHODS This cross-sectional study was performed in healthy residents who lived in Pekanbaru, Riau Province, Sumatera, for at least 6 months during forest fire disaster in 2015, and data were taken in October 2015. Questionnaires consisting of respiratory and non-respiratory symptoms were collected. Lung function was assessed by spirometry (MIR II Spirolab™ spirometer, Medical International Research, Italy) and exhaled carbon monoxide (CO) was assessed using piCO+ Smokerlyzer®. Heart rate at rest and oxygen saturation in the room air were measured using Onyx 9591 Pulse Oximeter®. RESULTS A total of 89 subjects were mostly female (75.3%), housewife (37.7%), nonsmoker (86.5%) with mean age of 38.9 years old. The non-respiratory and respiratory symptoms were reported in 84.7% and 71.4% subjects, respectively. Lung function was impaired in 72.6% subjects, mostly with mild obstruction and mild restriction. Exhaled CO was highly detected over normal values (mean [standard deviation] = 32.6 [9.97] ppm) with predicted carboxyhemoglobin (COHb) of 5.74 (1.56). CONCLUSIONS Forest fire smoke exposure increased the respiratory and nonrespiratory symptoms among healthy individuals, which showed impairment in lung function, exhaled CO, and predicted COHb. Long term health effects on healthy individuals exposed to forest fire smoke warrant further evaluation.

Mortality in a cohort of US firefighters from San Francisco, Chicago and Philadelphia: an update

OBJECTIVES

To update the mortality experience of a previously studied cohort of 29 992 US urban career firefighters compared with the US general population and examine exposure-response relationships within the cohort.

METHODS

Vital status was updated through 2016 adding 7 years of follow-up. Cohort mortality compared with the US population was evaluated via life table analyses. Full risk-sets, matched on attained age, race, birthdate and fire department were created and analysed using the Cox proportional hazards regression to examine exposure-response associations between select mortality outcomes and exposure surrogates (exposed-days, fire-runs and fire-hours). Models were adjusted for a potential bias from healthy worker survivor effects by including a categorical variable for employment duration.

RESULTS

Compared with the US population, mortality from all cancers, mesothelioma, non-Hodgkin's lymphoma (NHL) and cancers of the oesophagus, intestine, rectum, lung and kidney were modestly elevated. Positive exposure-response relationships were observed for deaths from lung cancer, leukaemia and chronic obstructive pulmonary disease (COPD).

CONCLUSIONS

This update confirms previous findings of excess mortality from all cancers and several site-specific cancers as well as positive exposure-response relations for lung cancer and leukaemia. New findings include excess NHL mortality compared with the general population and a positive exposure-response relationship for COPD. However, there was no evidence of an association between any quantitative exposure measure and NHL.