A longitudinal study of pulmonary function in fire fighters

Club Cells-A Guardian against Occupational Hazards

Club cells have a distinct role in the epithelial repair and defense mechanisms of the lung. After exposure to environmental pollutants, during chronic exposure, the secretion of club cells secretory protein (CCSP) decreases. Exposure to occupational hazards certainly has a role in a large number of interstitial lung diseases. According to the American Thoracic Society and the European Respiratory Society, around 40% of the all interstitial lung disease is attributed to occupational hazards. Some of them are very well characterized (pneumoconiosis, hypersensitivity pneumonitis), whereas others are consequences of acute exposure (e.g., paraquat) or persistent exposure (e.g., isocyanate). The category of vapors, gases, dusts, and fumes (VGDF) has been proven to produce subclinical modifications. The inflammation and altered repair process resulting from the exposure to occupational respiratory hazards create vicious loops of cooperation between epithelial cells, mesenchymal cells, innate defense mechanisms, and immune cells. The secretions of club cells modulate the communication between macrophages, epithelial cells, and fibroblasts mitigating the inflammation and/or reducing the fibrotic process. In this review, we describe the mechanisms by which club cells contribute to the development of interstitial lung diseases and the potential role for club cells as biomarkers for occupational-related fibrosis.

Decreased Pulmonary Function Over 5 Years in US Firefighters

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

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 ).

Lung function measures following simulated wildland firefighter exposures

Across the world, biomass smoke is a major source of air pollution and is linked with a variety of adverse health effects. This is particularly true in the western U.S. where wood smoke from wildland forest fires are a significant source of PM2.5. Wildland firefighters are impacted as they experience elevated PM2.5 concentrations over extended periods of time, often occurring during physical exertion. Various epidemiological studies have investigated wood smoke impacts on human health, including occupational field exposures experienced by wildland firefighters. As there are numerous challenges in carrying out these field studies, having the ability to research the potential health impacts to this occupational cohort in a controlled setting would provide important information that could be translated to the field setting. To this end, we have carried out a simulated wildland firefighter exposure study in a wood smoke inhalation facility. Utilizing a randomized crossover trial design, we exposed 10 participants once to clean filtered-air, 250 µg/m3, and 500 µg/m3 wood stove-generated wood smoke PM2.5. Participants exercised on a treadmill at an absolute intensity designed to simulate wildland firefighting for 1.5 hr. In addition to measured PM2.5 smoke concentrations, mean levels of CO2, CO, and % relative humidity were continuously monitored and recorded and were representative of occupational "real-world" exposures. Pulmonary function was measured at three time points: before, immediately after, and 1-hr post-exposure. Although there were some reductions in FVC, FEV1, and FVC:FEV1 measures, results of the spirometry testing did not show significant changes in lung function. The development of this wood smoke inhalational facility provides a platform to further address unique research questions related to wood smoke exposures and associated adverse health effects.

Chronic respiratory conditions in a cohort of metropolitan fire-fighters: associations with occupational exposure and quality of life

OBJECTIVES

To assess the prevalence of chronic respiratory conditions in metropolitan fire-fighters and to study associations between occupational exposure, use of respiratory protection and health-related quality of life (HRQoL) in fire-fighters with and without chronic respiratory conditions.

METHODS

Cross-sectional cohort analysis: Respiratory symptoms, medical conditions, occupational tasks and exposures and consistency of using respiratory protection were inquired by questionnaire. The SF12(®)V2 Health Survey was used to measure physical (PCS-12) and mental (MCS-12) HRQoL. Fire-fighters were categorised in subgroups: asthma; COPD/emphysema/chronic bronchitis; no chronic respiratory conditions; and as being 'not involved' or 'involved' in fire-fighting tasks, the latter further categorised as 'consistent' or 'inconsistent' use of respiratory protection. PCS-12 and MCS-12 scores were compared between subgroups and categories using linear regression.

RESULTS

Five hundred and seventy fire-fighters were analysed, 24 (4%) fulfilled the criteria for asthma, 39 (7%) for COPD/emphysema/chronic bronchitis. Fire-fighters with asthma were older than those in the other two subgroups and had been employed in the fire service longer. Respiratory subgroups did not differ in their involvement in fire-fighting tasks. Ninety-one percent of fire-fighters reported relevant occupational exposure in the past year. Mean PCS-12 scores for fire-fighters with no chronic respiratory conditions, asthma and COPD/emphysema/bronchitis were 52.0 (SD 6.9), 47.0 (8.5) and 48.1 (9.4). For PCS-12 (but not for MCS-12), interaction between having a chronic respiratory condition and inconsistent use of respiratory protection during fire knockdown was observed (p < 0.001).

CONCLUSIONS

Ten percent of metropolitan fire-fighters reported underlying chronic respiratory conditions. Presence of such a condition in combination with suboptimal protection from inhaled exposures may lead to poorer physical HRQoL.

Change in lung function over time in male metropolitan firefighters and general population controls: a 3-year follow-up study

OBJECTIVES

Previous studies in firefighters have been contradictory regarding their course of lung function over time. The aim of this ongoing study is to investigate how changes in lung function over time in male metropolitan firefighters compare with those in population controls, and to explore associations between firefighters' use of personal respiratory protection devices during occupational exposures and their risk of accelerated lung function decline.

METHODS

A prospective comparison of FEV1 (forced expiratory volume in 1 second) and FVC (forced vital capacity) was performed between 281 firefighters and 933 population controls. Logistic regression models were used to compare changes from baseline of FEV1 and FVC after 3 years and risk of accelerated decline between the cohorts. Within the firefighter cohort, risk of accelerated decline was compared between subgroups based on use of respiratory protection devices.

RESULTS

Controls showed similar mean annual declines for FEV1 and FVC across age categories, whereas firefighters aged <45 years showed increasing values over time (p=0.040). Firefighters had a lower odds of accelerated FEV1 decline compared with controls (OR=0.60, 95%CI 110.44; 0.83), but firefighters who never or rarely used respiratory protection during fire knockdown had a higher odds of accelerated FEV1 decline compared with those who used it often or frequently (OR=2.20, 95%CI 1.02; 4.74).

CONCLUSIONS

Younger generations of firefighters showed an increase in lung function relative to older colleagues, while population controls consistently showed decline of lung function across all ages. Firefighters who reported to be incompliant in using respiratory protection showed an increased risk of accelerated FEV1 decline.

Short-term spirometric changes in wildland firefighters

BACKGROUND

The short-term effects of smoke inhalation have been little studied in European wildland firefighters, especially in an intra-individual design. Our purpose is to study the spirometric changes from the early stage during a wildland fire season and to compare smokers and non-smokers.

METHODS

A population of 108 firefighters from a Civil Security Unit, based in Corsica, was tested immediately after having been exposed to the smoke of coniferous trees.

RESULTS

Out of 108 people, 59 were smokers and 49 were non-smokers without any acute or chronic pulmonary disease. Compared to baseline values, a decrease of spirometric parameters was observed immediately after the end of exposure and an even greater decrease was seen after 24 hr (FEV1 -0.53 L; FVC -0.59 L; PEF -53 L min(-1), P < 0.05 for each). None of the participants complained of respiratory symptoms. Three months after the end of the season, a final test was given which revealed a persistent decrease in spirometric parameters in comparison with baseline values (FEV1 -0.28 L; FVC -0.34 L; PEF -45 L min(-1), P < 0.05 for each). Comparison of smoking and non-smoking groups did not show any noteworthy difference for each parameter or the importance of their decline.

CONCLUSIONS

The findings show that firefighters are likely to develop respiratory impairments after wood smoke exposure. We did not observe any statistical differences between smokers and non-smokers.

Spirometry and impulse oscillometry (IOS) for detection of respiratory abnormalities in metropolitan firefighters

BACKGROUND AND OBJECTIVE

As firefighters are at increased risk of adverse health effects, periodic examination of their respiratory health is important. The objective of this study was to establish whether the use of impulse oscillometry (IOS) reveals respiratory abnormalities in metropolitan firefighters that go undetected during routine respiratory health screening by spirometry and assessment of respiratory symptoms.

METHODS

This was a cross-sectional analysis of spirometry, IOS and questionnaire data from 488 male firefighters. Abnormal spirometry was defined as FEV(1), FEV(1)/FVC and/or FEF(50) below the lower limit of normal. Abnormal IOS was defined as resistance at 5 Hz (R5), frequency dependence of resistance (DeltaR5-R20) and/or reactance area (AX) above the upper limit of normal. Respiratory symptoms, smoking history, exposures and medical history were assessed. Data were analysed using logistic and linear regression models.

RESULTS

The mean age of the firefighters was 43.8 (SD 8.4) years. There were 123 (25%) former smokers and 50 (10%) current smokers. Abnormal spirometry was detected in 12%, abnormal IOS in 9% and respiratory symptoms in 20% of firefighters. Current smoking was associated with all IOS parameters (OR for R5 = 3.1, OR for DeltaR5-R20 = 7.7, OR for AX = 4.3), and with FEF(50) (OR = 9.1), chronic productive cough (OR = 4.0) and breathlessness (OR = 5.4) (P < 0.05 for all). Exposure during firefighting duties was associated with chronic productive cough (OR = 2.6), but not with spirometry or IOS parameters. Interaction terms in the linear regression models indicated associations between smoking and DeltaR5-R20, and also between smoking and AX, in the lowest and second lowest quartiles of spirometry parameters.

CONCLUSIONS

Application of IOS for the assessment of respiratory health in firefighters identified airways dysfunction in some individuals, even when spirometry values were within the normal range and there were no respiratory symptoms.

Lung function and health status in metropolitan fire-fighters compared to general population controls

PURPOSE

To assess health status of South Australian (SA) metropolitan fire-fighters in terms of lung function and health-related quality of life, compare these with general population controls, and explore associations between fire-fighters' self-reported occupational exposure and health status.

METHODS

The study was a cross-sectional comparison of (respiratory) health indices between 501 fire-fighters and 1,324 general population controls taken from the North West Adelaide Health Study (NWAHS). All were men aged 21 to 61. Measurements included spirometry (i.e., forced expiratory volume in 1 s (FEV(1)), forced vital capacity (FVC), mid-expiratory flow (FEF(25-75)) and the Short Form 36 (SF-36) health-related quality of life questionnaire.

RESULTS

Health status in the fire-fighters was generally better than in NWAHS controls. Mean % predicted FEV(1) and FVC were 103.4% [SD 12.1] versus 89.5% [13.7] and 110.0% [11.6] versus 88.5% [12.5] (both p < 0.001 in linear regression analysis, adjusted for age, smoking, BMI, and FEV(1) % predicted). FEV(1)/FVC and FEF(25-75) were significantly lower in the fire-fighters (p < 0.003). A total of 93 (18.6%) fire-fighters and 82 (6.2%) controls had an FEV(1)/FVC < 70% (p < 0.001). The SF-36 Mental Health scale was the only scale on which fire-fighters had a lower mean score (p = 0.009), but none of the SF-36 scales showed clinically meaningful differences between the cohorts. Fire-fighters exposed > 6 h/week to dust, smoke, and fire showed lower FEV(1), FEV(1) % predicted, and FVC values compared to those who were less exposed (p < 0.05).

CONCLUSIONS

Male metropolitan fire-fighters showed better general health, better lung health, and similar mental health compared to general population controls. The high rate of fire-fighters with FEV(1)/FVC values below the recommended cut-point for airflow obstruction illustrates the inappropriateness of this clinical cut-point for use in populations preselected on their physical fitness. The observed dose-effect relationship between self-reported occupational exposure and fire-fighters' lung function warrants further investigation.

Respiratory protection programs for firefighters: a survey of practices for the state of Kentucky

OBJECTIVE

Firefighters play a crucial role as first responders in a variety of situations that can expose them to respiratory hazards. To ensure their safety and health, fire departments should have a respiratory protection program in place for all firefighters. A survey of Kentucky fire departments was conducted to assess their respiratory protection practices, barriers to program implementation, and medical evaluation programs.

METHOD

A 21-question survey assessing respiratory practices during the previous 12 months was mailed to all Kentucky fire departments.

RESULTS

A 62% survey response rate was achieved, with 116 of Kentucky's 120 counties returning at least one survey. All respondents indicated they were utilizing some type of respiratory protection, but only 37% indicated they had a written respiratory protection program. Compensation status and department sizes were found to be significant variables (p < 0.01) in determining if a fire department had a written respiratory protection program. Lack of funding (48%) and lack of understanding (39%) were cited as the greatest barriers to program implementation. Only 51% indicated they require their firefighters to receive a fit testing of their respirator, and 23% indicated they had a health-care provider who reviewed medical questionnaires or provided medical evaluations.

CONCLUSION

This survey indicates that many Kentucky fire departments are not meeting the legal and voluntary respiratory protection standards and guidelines, and demonstrates the need for improved education and funding to ensure that firefighters are adequately protected from respiratory hazards. This is particularly applicable to small rural volunteer departments, which had the greatest gap in compliance.

Woodsmoke health effects: a review

The sentiment that woodsmoke, being a natural substance, must be benign to humans is still sometimes heard. It is now well established, however, that wood-burning stoves and fireplaces as well as wildland and agricultural fires emit significant quantities of known health-damaging pollutants, including several carcinogenic compounds. Two of the principal gaseous pollutants in woodsmoke, CO and NOx, add to the atmospheric levels of these regulated gases emitted by other combustion sources. Health impacts of exposures to these gases and some of the other woodsmoke constituents (e.g., benzene) are well characterized in thousands of publications. As these gases are indistinguishable no matter where they come from, there is no urgent need to examine their particular health implications in woodsmoke. With this as the backdrop, this review approaches the issue of why woodsmoke may be a special case requiring separate health evaluation through two questions. The first question we address is whether woodsmoke should be regulated and/or managed separately, even though some of its separate constituents are already regulated in many jurisdictions. The second question we address is whether woodsmoke particles pose different levels of risk than other ambient particles of similar size. To address these two key questions, we examine several topics: the chemical and physical nature of woodsmoke; the exposures and epidemiology of smoke from wildland fires and agricultural burning, and related controlled human laboratory exposures to biomass smoke; the epidemiology of outdoor and indoor woodsmoke exposures from residential woodburning in developed countries; and the toxicology of woodsmoke, based on animal exposures and laboratory tests. In addition, a short summary of the exposures and health effects of biomass smoke in developing countries is provided as an additional line of evidence. In the concluding section, we return to the two key issues above to summarize (1) what is currently known about the health effects of inhaled woodsmoke at exposure levels experienced in developed countries, and (2) whether there exists sufficient reason to believe that woodsmoke particles are sufficiently different to warrant separate treatment from other regulated particles. In addition, we provide recommendations for additional woodsmoke research.

Longitudinal Decline in Lung Function: Evaluation of Interleukin-10 Genetic Polymorphisms in Firefighters

During annual medical monitoring, some firefighters are found to have rates of decline in forced expiratory volume in one second (FEV1) far exceeding their peers. Interleukin-10 (IL-10) suppresses inflammation, and single nucleotide polymorphisms (SNPs) in the IL-10 gene may confer variable susceptibility to more rapid decline in lung function. In 1204 firefighters with at least six annual FEV1 measurements, increased age and greater initial FEV1 were associated with more rapid decline in lung function. DNA collected from 379 of these firefighters was screened for IL-10 SNPs at -1117, -854, 919, 1668, and 1812. A statistically significant difference in decline in lung function was found based on genotyping at the 1668 SNP. Evaluation of gene polymorphisms regulating lung inflammation may help to explain some of the variation in rate of decline in lung function in firefighters.

Serum pneumoproteins: a cross-sectional comparison of firefighters and police

BACKGROUND

Serum pneumoproteins provide a measure of the permeability of the lower respiratory tract, and have shown promise as a biomarker of acute and chronic exposure to respiratory toxicants.

METHODS

To evaluate the effects of chronic occupational smoke exposure, 105 firefighters were compared with 44 police controls in a cross-sectional study using spirometry, diffusing capacity of the lung, serum Clara cell protein (CC16), and serum surfactant-associated protein A (SP-A) measurements.

RESULTS

There were no significant differences in age, gender, height, spirometry (FVC and FEV(1)), and diffusing capacity between the two groups. Serum SP-A was lower in firefighters (260.1 +/- 121.2 microg/L) than police (316.0 +/- 151.4 microg/L, P = 0.019). Serum CC16 was also lower in firefighters (8.39 +/- 3.11 microg/L) than police (10.56 +/- 4.20 microg/L, P < 0.001), although this difference lost statistical significance when adjusted for confounders.

CONCLUSIONS

Firefighters have lower serum concentrations of SP-A than do police. Although the clinical significance of this finding is presently unknown, SP-A deserves further study as a biomarker of toxic exposure to the lower respiratory tract.

Respiratory function in active firefighters

BACKGROUND

Exposure to environmental pollution during firefighting may results in the development of respiratory disorders in firefighters.

METHODS

The health effects of firefighting on respiratory function was investigated in a group of 128 active firefighters by recording respiratory symptoms and measuring lung function. In addition, 88 control workers, not exposed to known pollutants were studied for the prevalence of acute and chronic respiratory symptoms.

RESULTS

Significantly higher prevalences of dyspnea, nasal catarrh, sinusitis, and hoarseness were recorded in firefighters compared to control workers (P < 0.01). One subject developed asthma symptoms following two intense firefighting episodes. A high prevalence of acute symptoms experienced during and after fire extinguishing was also documented among these firefighters. Eye and throat irritation as well as headache were prominent. A logistic regression analysis of chronic respiratory symptoms demonstrated that odds ratios were significant for both duration of work exposure and for smoking. Lung function testing demonstrated a decrease in FEF75 in relation to predicted suggesting obstructive changes in the smaller airways. A regression analysis of ventilatory capacity tests indicated a positive relationship of forced vital capacity with length of employment, 1 s forced expiratory volume as well as FEF50 were related to smoking, and FEF75 was related to both smoking and length of employment.

CONCLUSIONS

Our data suggest that firefighters are at risk for developing acute and chronic respiratory symptoms as well as obstructive airway changes.

Adverse respiratory effects following overhaul in firefighters

Overhaul is the stage in which firefighters search for and extinguish possible sources of reignition. It is common practice not to wear respiratory protection during overhaul. Fifty-one firefighters in two groups, 25 without respiratory protection and 26 wearing cartridge respirators, were monitored for exposure to products of combustion and changes in spirometric measurements and lung permeability following overhaul of a structural fire. Testing at baseline and 1 hour after overhaul included forced vital capacity (FVC), forced expiratory volume in one second (FEV1), serum Clara cell protein (CC16), and serum surfactant-associated protein A (SP-A). Overhaul increased CC16 in both groups, indicating increased alveolarcapillary membrane permeability. Contrary to expectations, SP-A increased and FVC and FEV1 decreased in the firefighters wearing cartridge respirators. Changes in FEV1, CC16, and SP-A were associated with concentrations of specific products of combustion or carboxyhemoglobin levels. Firefighter exposures during overhaul have the potential to cause changes in spirometric measurements and lung permeability, and self-contained breathing apparatus should be worn during overhaul to prevent lung injury.

Longitudinal decline in measured firefighter single-breath diffusing capacity of carbon monoxide values. A respiratory surveillance dilemma

Seattle firefighters participate in a voluntary annual medical surveillance program including measurements of ventilatory capacity (FVC and FEV1) and single-breath diffusing capacity of carbon monoxide (DLCO). From 1989 to 1996, average % predicted DLCO (Crapo) for all participating firefighters declined from 94.4% (95% confidence interval [CI]: 93.4% to 95.5%) to 87.3% (95% CI: 86.2% to 88.3%), with no significant change in average FVC or FEV1. A random-effects regression model based on data from 812 firefighters with at least two annual sets of DLCO measurements showed the expected associations between DLCO and age, height, gender, race, ventilatory capacity, and smoking. In addition, two important temporal changes were observed, including, for an average firefighter, a large mean decline in DLCO of -1.02 ml/min/mm Hg associated with year of measurement, and a relatively smaller decline of -0.006 ml/min/mm Hg associated with number of fires fought. Although the stability of ventilatory capacity over time is reassuring, the marked temporal decline in diffusing capacity among this population of firefighters raises issues of concern. Interpretation of the observed decline poses a dilemma in terms of the reliability and efficacy of diffusing capacity as a screening tool, in whether DLCO is subject to unacceptable technical variability or whether it might provide more sensitive detection of early adverse respiratory effects of smoke inhalation.

Variable extrathoracic airflow obstruction and chronic laryngotracheitis in Gulf War veterans

STUDY OBJECTIVES

To study the flow-volume loop for evidence of variable extrathoracic airflow obstruction in Persian Gulf War veterans.

DESIGN

Retrospective case-control, single-center study.

SETTING

The pulmonary division of an academic health-care center.

SUBJECTS

A convenience sample of the Persian Gulf Registry.

MEASUREMENTS AND INTERVENTIONS

(1) Midvital capacity ratio (ratio of maximum forced midexpiratory to maximum forced midinspiratory flow). This ratio is the criterion standard for the diagnosis of variable extrathoracic airflow obstruction. (2) Evaluation of the anatomy and function of the extrathoracic airway by fiberoptic bronchoscopy. (3) Further investigation into the airway abnormality by histologic evaluation of tracheal biopsy samples in Gulf War veterans only.

RESULTS

Midvital capacity was > 1.0 in 32 of 37 Gulf War veterans compared with only 11 of 38 control subjects. The mean (+/-SD) value was 1.37+/-0.4 among Gulf War veterans and 0.88+/-0.3 among control subjects (p=0.0000005). FVC and its ratio to FEV1 were normal in all these subjects. Bronchoscopy showed inflamed larynx and trachea in all (n=17) Gulf War veterans. Histologic study showed chronic inflammation of the trachea in everyone (n=12) who had an adequate biopsy sample.

CONCLUSION

Physicians should be made aware of the presence of chronic inflammation of the upper airways and inspiratory airflow limitation in a number of Gulf War veterans.

Late pulmonary sequela following burns: persistence of hyperprocalcitonemia using a 1-57 amino acid N-terminal flanking peptide assay

Seven patients were evaluated at a mean duration of 8.4 yr after sustaining inhalational injury associated with burns. At the time of re-examination, the patients were asymptomatic and had normal chest X-rays, and arterial blood gases. Three of the seven patients had abnormally elevated serum calcitonin levels. The spirometry (FEV1) measurements showed an inverse trend to that of the serum calcitonin levels. The elevated calcitonin levels had an abnormal predominance of the procalcitonin component as assessed by several region specific antisera. The serum calcitonin also showed a significant correlation with the hormone level which had been obtained at the time of prior discharge from the hospital (r = 0.91). Although there appears to be no or minimal chronic pulmonary sequela to inhalational injury in burns by pulmonary testing, we speculate that the hyperprocalcitonemia in some of the patients may reflect a long-term hyperplastic response of the bronchio-epithelial pulmonary neuroendocrine cells. The potential significance of this and other lung-associated endocrine markers is discussed.

Mortality among fire fighters in metropolitan Toronto

Fire fighters are exposed to substances which are recognized or suspected causal agents in cancer or heart disease. The purpose of this study was to determine whether or not fire fighters experience increased risk for any specific cause of death. A retrospective cohort study was conducted, with 5,995 subjects recruited from all six fire departments within Metropolitan Toronto. The mortality experience of the cohort was ascertained through computerized record linkage and compared to that of the male Ontario population specific to cause, age, and calendar period from 1950 through 1989. Average duration of follow-up was 21 years, and there were 777 deaths among the 5,414 males included in the analysis, giving an all-cause standardized mortality ratio of 95 (95% confidence interval: 88-102). Three specific causes of death exhibit statistically significant excesses (brain tumors, "other" malignant neoplasms, and aortic aneurysms). There are also slight increases in risk for some other sites of cancer, and for various diseases of the respiratory, circulatory, and digestive systems. This study is consistent with others in demonstrating that fire fighters experience increased risk of death from cancer of the brain, and in suggesting increased risk for various other causes of death.

The effect of smoke inhalation on lung function and airway responsiveness in wildland fire fighters

The current study was undertaken to evaluate the effect of smoke on forced expiratory volumes and airway responsiveness in wildland fire fighters during a season of active fire fighting. Sixty-three seasonal and full-time wildland fire fighters from five U.S. Department of Agriculture Forest Service (USDAFS) Hotshot crews in Northern California and Montana completed questionnaires, spirometry, and methacholine challenge testing before and after an active season of fire fighting in 1989. There were significant mean individual declines of 0.09, 0.15, and 0.44 L/s in postseason values of FVC, FEV1, and FEF25-75, respectively, compared with preseason values. There were no consistent significant relationships between mean individual declines of the spirometric parameters and the covariates: sex, smoking history, history of asthma or allergies, years as a fire fighter, upper/lower respiratory symptoms, or membership in a particular Hotshot crew. There was a statistically significant increase in airway responsiveness when comparing preseason methacholine dose-response slopes (DRS) with postseason dose-response slopes (p = 0.02). The increase in airway responsiveness appeared to be greatest in fire fighters with a history of lower respiratory symptoms or asthma, but it was not related to smoking history. These data suggest that wildland fire fighting is associated with decreases in lung function and increases in airway responsiveness independent of a history of cigarette smoking. Our findings are consistent with the results of previous studies of municipal fire fighters.