Lung function in fire fighters, I: a three year follow-up of active subjects

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 ).

Longitudinal pulmonary function in newly hired, non-World Trade Center-exposed fire department City of New York firefighters: the first 5 years

BACKGROUND

Few longitudinal studies characterize firefighters’ pulmonary function. We sought to determine whether firefighters have excessive FEV(1) decline rates compared with control subjects.

METHODS

We examined serial measurements of FEV(1) from about 6 months prehire to about 5 years posthire in newly hired male, never smoking, non-Hispanic black and white firefighters, hired between 2003 and 2006, without prior respiratory disease or World Trade Center exposure. Similarly defined Emergency Medical Service (EMS) workers served as control subjects.

RESULTS

Through June 30, 2011, 940 firefighters (82%) and 97 EMS workers (72%) who met study criteria had four or more acceptable posthire spirometries. Prehire FEV(1) % averaged higher for firefighters than EMS workers (99% vs 95%), reflecting more stringent job entry criteria. FEV(1) (adjusted for baseline age and height) declined by an average of 45 mL/y both for firefighters and EMS workers, with Fire 2 EMS decline rate differences averaging 0.2 mL/y (CI, 2 9.2 to 9.6). Four percent of each group had FEV(1) less than the lower limit of normal before hire, increasing to 7% for firefighters and 17.5% for EMS workers, but similar percentages of both groups had adjusted FEV(1) decline rates 10%. Mixed effects modeling showed a significant influence of weight gain but not baseline weight: FEV(1) declined by about 8 mL/kg gained for both groups. Adjusting for weight change, FEV(1) decline averaged 38 mL/y for firefighters and 34 mL/y for EMS workers.

CONCLUSIONS

During the first 5 years of duty, firefighters do not show greater longitudinal FEV(1) decline than EMS control subjects, and fewer of them develop abnormal lung function. Weight gain is associated with a small loss of lung function, of questionable clinical relevance in this fit and active population.

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.

Pulmonary function predicting confirmed recovery from lower-respiratory symptoms in World Trade Center-exposed firefighters, 2001 to 2010

BACKGROUND

We examined the relationship between pulmonary function (FEV 1 ) and confirmed recovery from three lower-respiratory symptoms (LRSs) (cough, dyspnea, and wheeze) up to 9 years after symptom onset.

METHODS

The study included white and black male World Trade Center (WTC)-exposed firefighters who reported at least one LRS on a medical monitoring examination during the fi rst year after September 11, 2001. Confirmed recovery was defined as reporting no LRSs on two consecutive and all subsequent examinations. FEV 1 was assessed at the fi rst post-September 11, 2001, examination and at each examination where symptom information was ascertained. We used stratified Cox regression models to analyze FEV 1 , WTC exposure, and other variables in relation to confirmed symptom recovery.

RESULTS

A total of 4,368 fi refighters met inclusion criteria and were symptomatic at year 1, of whom1,592 (36.4%) experienced confirmed recovery. In univariable models, fi rst post-September 11,2001, concurrent, and difference between fi rst post-September 11, 2001, and concurrent FEV 1 values were all significantly associated with confirmed recovery. In adjusted analyses, both fi rst post-September 11, 2001, FEV 1 (hazard ratio [HR], 1.07 per 355-mL difference; 95% CI, 1.04-1.10) and FEV 1 % predicted (HR, 1.08 per 10% predicted difference; 95% CI, 1.04-1.12) predicted confirmed recovery. WTC exposure had an inverse association with confirmed recovery in the model with FEV 1 , with the earliest arrival group less likely to recover than the latest arrival group (HR, 0.73;95% CI, 0.58-0.92).

CONCLUSIONS

Higher FEV 1 and improvement in FEV 1 after September 11, 2001, predicted confirmed LRS recovery, supporting a physiologic basis for recovery and highlighting consideration of spirometry as part of any postexposure respiratory health assessment.

Exploring occupational and behavioral risk factors for obesity in firefighters: a theoretical framework and study design

Firefighters and police officers have the third highest prevalence of obesity among 41 male occupational groups in the United States (US). However, few studies have examined the relationship of firefighter working conditions and health behaviors with obesity. This paper presents a theoretical framework describing the relationship between working conditions, health behaviors, and obesity in firefighters. In addition, the paper describes a detailed study plan for exploring the role of occupational and behavioral risk factors in the development of obesity in firefighters enrolled in the Orange County Fire Authority Wellness Fitness Program. The study plan will be described with emphasis on its methodological merits: adopting a participatory action research approach, developing a firefighter-specific work and health questionnaire, conducting both a cross-sectional epidemiological study using the questionnaire and a sub-study to assess the validity of the questionnaire with dietary intake and physical activity measures, and evaluating the strengths and weaknesses of the body mass index as an obesity measure in comparison to skinfold-based percent body fat. The study plan based on a theoretical framework can be an essential first step for establishing effective intervention programs for obesity among professional and voluntary firefighters.

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.

Lung function in rescue workers at the World Trade Center after 7 years

BACKGROUND

The terrorist attacks on the World Trade Center on September 11, 2001, exposed thousands of Fire Department of New York City (FDNY) rescue workers to dust, leading to substantial declines in lung function in the first year. We sought to determine the longer-term effects of exposure.

METHODS

Using linear mixed models, we analyzed the forced expiratory volume in 1 second (FEV(1)) of both active and retired FDNY rescue workers on the basis of spirometry routinely performed at intervals of 12 to 18 months from March 12, 2000, to September 11, 2008.

RESULTS

Of the 13,954 FDNY workers who were present at the World Trade Center between September 11, 2001, and September 24, 2001, a total of 12,781 (91.6%) participated in this study, contributing 61,746 quality-screened spirometric measurements. The median follow-up was 6.1 years for firefighters and 6.4 years for emergency-medical-services (EMS) workers. In the first year, the mean FEV(1) decreased significantly for all workers, more for firefighters who had never smoked (a reduction of 439 ml; 95% confidence interval [CI], 408 to 471) than for EMS workers who had never smoked (a reduction of 267 ml; 95% CI, 263 to 271) (P<0.001 for both comparisons). There was little or no recovery in FEV(1) during the subsequent 6 years, with a mean annualized reduction in FEV(1) of 25 ml per year for firefighters and 40 ml per year for EMS workers. The proportion of workers who had never smoked and who had an FEV(1) below the lower limit of the normal range increased during the first year, from 3% to 18% for firefighters and from 12% to 22% for EMS workers, stabilizing at about 13% for firefighters and 22% for EMS workers during the subsequent 6 years.

CONCLUSIONS

Exposure to World Trade Center dust led to large declines in FEV(1) for FDNY rescue workers during the first year. Overall, these declines were persistent, without recovery over the next 6 years, leaving a substantial proportion of workers with abnormal lung function.

Effect of protective filters on fire fighter respiratory health: field validation during prescribed burns

BACKGROUND

Bushfire smoke contains a range of air toxics. To prevent inhalation of these toxics, fire fighters use respiratory equipment. Yet, little is known about the effectiveness of the equipment on the fire ground. Experimental trials in a smoke chamber demonstrated that, the particulate/organic vapor/formaldehyde (POVF) filter performed best under simulated conditions. This article reports on the field validation trials during prescribed burns in Western Australia.

METHODS

Sixty-seven career fire fighters from the Fire and Emergency Services Authority of Western Australia were allocated one of the three types of filters. Spirometry, oximetry, self-reported symptom, and personal air sampling data were collected before, during and after exposure to bushfire smoke from prescribed burns.

RESULTS

Declines in FEV(1) and SaO(2) were demonstrated after 60 and 120 min exposure. A significant higher number of participants in the P filter group reported increases in respiratory symptoms after the exposure. Air sampling inside the respirators demonstrated formaldehyde levels significantly higher in the P filter group compared to the POV and the POVF filter group.

CONCLUSIONS

The field validation trials during prescribed burns supported the findings from the controlled exposure trials in the smoke chamber. Testing the effectiveness of three types of different filters under bushfire smoke conditions in the field for up to 2 hr demonstrated that the P filter is ineffective in filtering out respiratory irritants. The performance of the POV and the POVF filter appears to be equally effective after 2 hr bushfire smoke exposure in the field.

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.

Medical surveillance of hazardous materials response fire fighters: a two-year prospective study

Hazardous materials releases can cause substantial morbidity and mortality, and an increasing number of communities have developed hazardous materials (HAZMAT) teams to deal with such incidents. Little is known, however, about the health effects of chemical accidents on HAZMAT team participants. Baseline and periodic medical surveillance of all 40 fire fighters from the Metrofire Haz-mat team was conducted in 1992/1993 and 1995, respectively. A database on incidents responded to by the team during the study period was also developed. From June 1990 through April 1995, the team responded to a total of 34 hazardous materials incidents. No injuries to HAZMAT team members were reported. Few biochemical abnormalities were observed, and those that were could not be linked to specific exposures or incidents. Four individuals had abnormal audiometry on both occasions. There was a trend toward a lower percent predicted FEV1 for the entire group on follow-up: 106 +/- 13% vs 105 +/- 12%, P = 0.07. For fire fighters older than age 35 (n = 21), the percent predicted FEV1 was significantly lower at follow-up: 108 +/- 12% vs 106 +/- 14%, P = 0.01. The results suggest significant noise exposure and exposure to pulmonary irritants, which support the use of baseline and periodic audiometry and spirometry. The potential utility of other laboratory testing is also discussed.

Mortality of urban firefighters in Alberta, 1927-1987

The mortality experience of firefighters has been an active topic of investigation. Collateral toxicological evidence suggests that certain causes of death are likely to be associated with firefighting: lung cancer, heart disease, and obstructive pulmonary disease. To date there has not been a clear and consistent demonstration of excess risk due to occupational exposure for these outcomes, but certain other cancers, including genitourinary, colon and rectum, and leukemias, lymphomas, and myeloma, appear to be consistently elevated. A major unproven hypothesis is that risk increased following the introduction, in the 1950s of combustible plastic furnishing and building materials known to generate toxic combustion products. Mortality by cause of death was examined for two cohorts totalling 3,328 firefighters active from 1927 to 1987 in Edmonton and Calgary, the two major urban centers in the province of Alberta, Canada, examining associations with cohort (before and after the 1950s) and years of service weighted by exposure opportunity. The study attained 96% follow-up of vital status and over 64,983 person-years of observation, yielding 370 deaths. Mortality from all causes was close to the expected standardized mortality ratio (96; 95% confidence limits (CL) 87, 107) as was that for heart disease (110; 95% CL 92, 131), and neither was statistically significant at the p < 0.05 level (N.S.). Excesses were observed for all malignant neoplasms (127; 95% CL 102, 155, p < 0.05) and for cancer of lung (142; 95% CL 91, 211, N.S.), bladder (315; 95% CL 86, 808, N.S.), kidney and ureter (414; 95% CL 166, 853, p < 0.05), colon and rectum (161; 95% CL 88, 271, N.S.), pancreas (155; 95% CL 50, 362, N.S.) and leukemia, lymphoma, and myeloma (127; 95% CL 61, 233, N.S.); obstructive pulmonary diseases (157; 95% CL 79, 281, N.S.). Fire-related causes showed a marked excess (486; 95% CL 233, 895, p < 0.01), but external causes overall showed a significant deficit (66; 95% CL 49, 87, p < 0.05). The lung cancer excess was confined to Edmonton; there was no consistent association with duration of employment, exposure opportunity, or cohort of entry (before or after the 1950s) except that the highest risk was observed among Edmonton firefighters with over 35 weighted years. The excess of cancers of the urinary tract was observed mostly among firefighters entering service after 1950, appeared to increase with length of service and exposure opportunity, and was observed in both cities. An occupational association with heart disease and chronic pulmonary disease is not supported in this study on this population.(ABSTRACT TRUNCATED AT 400 WORDS)

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.

Human factors in firefighting: ergonomic-, cardiopulmonary-, and psychogenic stress-related issues

There are many issues in firefighting that involve human factors and cardiopulmonary conditioning. Population-based mortality and disability surveillance studies suggest a relatively small but significant excess of disability but not mortality from nonmalignant cardiovascular disease for firefighters. More targeted cohort and case-control studies do not support such an excess and instead suggest a strong healthy worker effect. Pulmonary function among firefighters has been extensively studied, with contradictory findings. Extreme exposures and long-term exposure in combination with cigarette smoking may be risk factors for respiratory disorders and accelerated decline in airflow. It appears likely that individual firefighters who show early signs of illness are often selectively transferred out of active firefighting positions. Despite exposure to substances such as carbon monoxide that may predispose to cardiovascular mortality and morbidity, excesses are not consistently shown in mortality studies. Clinical studies of individual firefighters do suggest an elevated risk for myocardial ischemia. The ergonomic demands of firefighting are extreme at peak activity because of high energy costs for activities such as climbing aerial ladders, the positive heat balance from endogenous and absorbed environmental heat, and encumbrance by bulky but necessary protective equipment. The psychological stresses of firefighting include long periods of relative inactivity punctuated by highly stressful alarms and extremely stressful situations such as rescues, as reflected in physiological and biochemical indicators. Firefighters are at risk for depression and post-traumatic stress disorder, although morale overall is generally much higher than in comparable occupations. Women firefighter candidates as a group perform less well on selection test simulating the demands of active firefighting, but some individual women perform very well.

An epidemiologic study of cancer and other causes of mortality in San Francisco firefighters

To test the hypothesis that firefighter exposures may increase cancer risk, mortality rates were calculated for 3,066 San Francisco Fire Department firefighters employed between 1940 and 1970. Vital status was ascertained through 1982, and observed and expected rates, rate ratios (RR), and 95% confidence intervals (CI) were computed using United States death rates for comparison. The total number deceased (1,186) was less than expected and there were fewer cancer deaths than expected. However, there were significant excess numbers of deaths from esophageal cancer (12 observed, 6 expected), cirrhosis and other liver diseases (59 observed, 26 expected), and accidental falls (21 observed, 11 expected). There were 24 line-of-duty deaths, which were primarily due to vehicular injury, falls, and asphyxiation. Heart disease and respiratory disease deaths occurred significantly less often than expected. It was concluded that the increased risks of death from esophageal cancer and cirrhosis and other liver diseases may have been due to firefighter exposures, alcohol consumption, or interaction between alcohol and exposures. Because this was an older cohort and firefighter exposures have changed due to the increasing use of synthetic materials, it is recommended that the effects of modern-day exposures be further studied.

A longitudinal study of pulmonary function in fire fighters

Pulmonary function changes among fire fighters were evaluated by re-examining 632 Baltimore city fire fighters six to ten years after a baseline examination. Spirometry was used to determine forced expiratory volume in 1 second (FEV1). Information about exposures was obtained by questionnaire and by combining data from fire department records regarding the number of fires fought by fire fighting units with individual work histories. Men who never wore a mask while extinguishing fires experienced a 1.7 times greater rate of FEV1 decline than mask wearers. Men with ammonia exposure experienced a rate of decline 1.7 times greater than non-exposed men. Neither length of time spent in exposed jobs nor number of responses were associated with the rate of decline. Active fire fighters experienced a rate of decline 2.5 times greater than those who had retired or resigned. Some effects differed between men who were able to perform repeatable pulmonary function tests and those who were not.

Respiratory mortality among firefighters

Although firefighters have been shown in some studies to suffer chronic respiratory morbidity from their occupational exposures, an increased risk for dying from non-malignant respiratory diseases has not been documented in any previous retrospective cohort mortality study. In order to assess the possibility that an unusually strong "healthy worker effect" among firefighters might mask this increased risk, a mortality analysis of firefighters was carried out in three cities in relation to the United States population and also to a comparison cohort of police officers. The firefighters were employed between 1945 and 1980 and experienced 886 deaths by 1 January 1984; compared with the United States population they had a significantly reduced risk of dying from all causes (SMR = 82, 95% confidence interval, 77-87), and from non-malignant circulatory diseases (SMR = 81, 95% confidence interval 73-89), but no significant difference in risk of non-malignant respiratory diseases (SMR = 88, 95% confidence interval 66-117). Compared with police, the firefighters experienced a trend toward improved mortality outcomes for all causes investigated (SMR = 82), but they had an excess of deaths from non-malignant respiratory diseases (SMR = 141). The results indicate that firefighters are probably at increased risk for dying from non-malignant respiratory diseases; this increased risk may have been missed in previous studies because of the limitations of using a general reference population.

The short-term effects of smoke exposure on the pulmonary function of firefighters

The short-term effects of smoke inhalation have been little studied. This study evaluated whether firefighters experience a significant change in spirometric values following exposure to smoke from a fire. Sixty firefighters from the city of Pittsburgh completed a questionnaire (Medical Research Council) and underwent spirometric testing following exposure to house fires. The group contained 25 current smokers, 14 ever smokers, and 21 never smokers. Firefighters reporting cough, phlegm, breathlessness, and chest illnesses were more likely to be current or ever smokers than never smokers. Mean spirometric data obtained before exposure, after a minimum of four off-duty days, showed the following: FVC, 4.50 +/- 0.60L (90 percent of predicted); FEV1, 3.65 +/- 0.56L (96 percent of predicted); FEV1/FVC, 81 +/- 8 percent (106 percent of predicted); FEF25-75%, 3.71 +/- 1.13L/s (96 percent of predicted); and PEF, 7.95 +/- 1.70L/s (87 percent of predicted). After exposure, spirometry was performed on 22 firefighters. All spirometric values decreased after exposure; however, a significant decline was only seen in two indices, the FEV1 and FEF25-75%. This decline was small (3 to 11 percent). Two firefighters experienced an exaggerated decline in spirometric values after exposure, compared to the group as a whole. Neither age, smoking history, location of firefighting, intensity of smoke exposure, or use of a self-contained breathing apparatus explained the reasons for the greater decline in these two individuals. Thus, while firefighters do experience a small decrease in pulmonary function after exposure to house fires, there appears to be a small subgroup of firefighters who develop more substantial and potentially clinically important decreases in pulmonary function after smoke exposure.

Mortality of a municipal-worker cohort: IV. Fire fighters

Morbidity and mortality studies of fire fighters have produced varied and inconsistent findings regarding the potential chronic effects of fire fighting including respiratory disease, cardiovascular disease, and cancer. The mortality experience of 1,867 white male fire fighters who were employed for the City of Buffalo a minimum of five years with at least one year as a fire fighter was studied. Vital status was determined for 99% of the cohort, resulting in 470 observed deaths. The fire fighter cohort was characteristic of a healthy worker population. All-cause mortality was close to the expected standardized mortality ratio (SMR) = 95, and significantly lower than expected mortality was seen for all external causes (SMR = 67)--in particular, for suicide (SMR = 21) and respiratory diseases (SMR = 48). Significantly elevated SMRs were found for benign neoplasms (SMR = 417), cancer of the colon (SMR = 183), and cancer of the bladder (SMR = 286). Cause-specific mortality is presented by number of years employed, calendar year of death, year of hire, and latency. Cancer mortality was significantly higher in the long-term fire fighters, and risk of mortality from all malignant neoplasms tended to increase with increasing latency. Patterns in risk of mortality among fire fighters for cancers of the bladder, colon, and brain are intriguing. Additional follow-up of this cohort and initiation of cancer morbidity studies would be helpful in further clarifying the potential long-term effects of fire fighting on cancer risk.

Ischemic heart disease mortality of firemen and policemen

Ischemic heart disease (IHD) mortality of Connecticut firemen and policemen is studied for the years 1960-78, using death certificate data. The mortality of these two occupations is expected to be greater than that of other workers. Standardized Mortality Odds Ratios for firemen and policemen are greater than 1.00. Although some increased IHD risk for firemen and policemen is suggested, the exact role of occupational risk factors remains to be determined.

Mortality in police and firefighters in New Jersey

A proportionate mortality study of police and firefighters in New Jersey was conducted using the records of a comprehensive retirement system. Three reference populations were used: U.S. general population, New Jersey general population, and police as a reference group for the firefighters. Overall neither group differed from the New Jersey male population in the cause of death. Analyses by latency showed an increase in skin cancer and cirrhosis in firefighters and cirrhosis in police. With increased time from first employment, an inverse association was found between heart disease and time of first exposure. This was reflected in statistically significant increased proportionate mortality rates (PMR) for arteriosclerotic heart disease (ASHD) (ICD 410-414) for both working police (PMR = 1.15) and firefighters (PMR = 1.2). Retired police and firefighters had PMRs of 0.96 and 0.98, respectively. Firefighters had a significant increase in nonmalignant respiratory disease (PMR = 1.98) and leukemia (PMR = 2.76) when the police were used as a reference group. Potential causes of the above findings are discussed.

Pulmonary function of London firemen

In a longitudinal study of a sample of firemen in London 1006 firemen were interviewed and examined in 1976 and 895 were seen a second time 12 months later. On each occasion a Medical Research Council respiratory questionnaire was administered and forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) were measured. The average levels of FEV1, FVC, and FEV1/FVC in both years compared favourably with conventional predicted values. Separate multiple regression analysis for the two years indicated that the FEV1 and FVC fell more rapidly in those aged over 40, and that cigarette smoking had a strong harmful effect on these measures of function. Only among men with over 20 years' service was there possibly any evidence (not statistically significant) of an effect from duration of employment. The comparatively large fall in FEV1 and FVC from 1976 to 1977 was due mainly to instrumental variation. The prevalence of respiratory symptoms was higher in smokers than non-smokers and increased with the number of cigarettes smoked.

Mortality of fire fighters in Western Australia

All except 17 (1.7%) of 990 fire fighters employed by the Western Australian Fire Brigade between 1 October 1939 and 31 December 1978 were successfully followed up to 31 December 1978. Mortality from all causes was less than expected (SMR 0.80 with 95% confidence interval 0.67 to 0.96). There was evidence of the healthy worker effect but none that mortality increased with increasing duration of employment. A small proportional excess of deaths from road traffic accidents ( SPMR 1.66) appeared to be unrelated to fire service. Deaths from other accidents, poisonings, and violence were significantly less than expected (SMR 0.35 with 95% confidence interval 0.10 to 0.90) and may indicate an effect of training and experience on accident proneness. There was no evidence of increased mortality from cardiovascular or respiratory disease, or from any other cause.

Occupational exposure and 12-year spirometric changes among Paris area workers

A follow-up study over 12 years was conducted among 556 men aged 30 to 54 in 1960 and working at that time in factories around Paris (France). Various occupational exposures were recorded at the time of the 1960 survey after a technical study of each workplace. The annual rate of decline of FEV1 during 12 years was estimated for each subject from the measurements in 1960 and 1972. This rate (the FEV1 slope) was related independently of FEV1 level (which reflects the loss since the beginning of adult life) and of smoking habits to occupational exposure to dust, gases, and heat. FEV1 slope was significantly related to inhalation of mineral dust (even in the absence of silica) as well as to grain dust, and the slope was steeper with increased intensity of exposure to dust. Analysis of job changes showed that among heavily exposed subjects, those who changed jobs had a less steep slope than those who did not. Our results support the hypothesis of a causal role of exposure to dust in the development of chronic airflow obstruction and of a benefit when exposure to dust ceases. Exposure to dust, gas, and heat usually occurred together so data on gas and heat were analysed after taking account of exposure to dust. The influence of heat on FEV1 decline showed a clear trend. Results suggest that exposure to gases associated with exposure to dust or heat or both had a deleterious effect. After adjusting for age, smoking, and FEV1 level (ASLA) the following average slopes were obtained: 44 ml/a (for exposure to none or to only a slight amount of dust, or to gases alone), 51 ml/a (heat), 53 ml/a (noticeable dust), 55 ml/a (noticeable dust and heat), 60 ml/a (noticeable dust, heat, and high concentration of gases). Independently of the occupational exposures, ASLA FEV1 slopes among manual workers were related to skill, being 44 ml/a for skilled and 51 ml/a for unskilled men. Independently of social class and occupational exposures recorded, there were differences in FEV1 slopes by factory, suggesting that one should not rely on using one factory as the control of studies of occupational exposure to another.

Pulmonary function in firefighters: a six-year follow-up in the Boston Fire Department

Tests of ventilatory capacity, objective cough, and standardized respiratory questionnaires were used in a prospective study to measure the effect of firefighting on pulmonary function in a cohort of 951 white Boston firefighters between 1970-1976. During the six years of follow-up, the mean annual decrements in forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) were 36 and 29 ml per year, respectively. At the end of the study in 1976, the mean FEV1 for this group was 98.3% of the level predicted for healthy nonsmoking adults, while the FVC was 97.8%. Current cigarette smoking was associated with an increased prevalence of bronchitis, a loose cough, reduced levels of FEV1 and FVC, and increased longitudinal changes in FEV1 and FVC. The longitudinal changes and current levels of FEV1 and FVC were not correlated with any index of firefighting exposure in active firefighters. Increased use of protective respiratory apparatus and previously described selection effects within the Boston Fire Department appear to be protecting this group of firefighters from long-term effects of smoke exposure as measured by these techniques.

Smoke inhalation in firemen

Thirty firemen were studied with pulmonary function tests immediately after a severe smoke exposure and then one and a half and 18 months later in order to evaluate acute and chronic changes in their spirometry. The results were compared with predicted values and with those from a group of closely matched control subjects. We found no significant differences between the acute post-exposure spirometry values and those recorded at six weeks and 18 months later. A trend toward an increased rate of volume loss in the FVC and FEV1 was noted which is similar to other published observations. However, we did find a significant decrement in FVC compared with predicted value, and in FVC and FEV1 compared with control subjects. This is further evidence that firemen may develop lung disease related to their occupational exposure.

Chronic respiratory disease and respiratory function in a group of fire fighters

A sample of 193 subjects drawn from the New South Wales Fire Brigade was studied to examine the prevalence of chronic respiratory disease and impairment of respiratory function. The prevalence of respiratory disease was less than that reported in other groups of firemen and reflects the lower level of occupational exposure, and possibly a survivor effect, within the New South Wales Fire Brigade. Among recent recruits, the effects of cigarette smoking far outweighed any contribution from occupational exposure. Among firemen with 20 years or more service a twofold increase in the prevalence of chronic bronchitis is considered to result from the additive effects of cigarette smoking and the high occupational smoke exposures consequent to the availability of respiratory protection and earlier attitudes to its use. The increasingly toxic nature of combustion products at fires was not accompanied by a discernible increase in the prevalence of chronic respiratory disease or impairment of respiratory function. The major combustion products responsible for respiratory damage were self-administered, arising from burning tobacco rather than from burning buildings.

Acute and chronic effects of fire fighting on pulmonary function

The acute and chronic effects of fire fighting on pulmonary function were studied in 54 fire fighters from Connecticut, 32 smokers and 22 nonsmokers. Baseline studies of maximum expiratory flow-volume curves while breathing air and a mixture of 80 percent helium and 20 percent oxygen revealed obstruction of the small airways in 35 percent (nine) of 26 smokers and 13 percent (two) of 15 nonsmokers. Cigarette smoking appears to be a major contributor to obstruction of the airways in fire fighters. In the nonsmoking group, disease of the small airways was present only in fire fighters with at least 25 years of fire fighting, and none of them had respiratory complaints. In seven fire fighters retested immediately following mild exposure to a fire in a building, no significant changes in pulmonary function were noted. One fire fighter trapped in a fire in a basement had a high level of carboxyhemoglobin (42 percent) and developed a severe obstructive ventilatory defect which persists 2 1/2 years after the fire. The significance of disease of the small airways in fire fighters with chronic exposure remains to be elucidated with long-term studies; however, acute significant exposure may be associated with irreversible pulmonary injury in fire fighters.

Pulmonary function in firefighters: acute changes in ventilatory capacity and their correlates

A group of 39 firefighters was examined during routine firefighing duty. Following smoke exposure the average decrease in one-second forced expiratory volume (FEV1.0) was 0.05 litre (137 observations). This decline in FEV1.0 was related to the severity of smoke exposure as estimated by the firefighter and to the measured particulate concentration of the smoke to which he was exposed. Decreases in FEV1.0 in excess of 0.10 litre were recorded in 30% of observations. Changes in FEV1.0 resulting from a second exposure to smoke on the same tour of duty were greater when smoke exposure at the previous fire was heavy. The repeated episodes of irritation of the bronchial tree that have been documented in this investigation may explain the origin of the previously observed chronic effect of firefighting on respiratory symptoms and pulmonary function.

Mortality among Boston firefighters, 1915--1975

Although the nature of firefighting involves particular health hazards, previous mortality and morbidity studies of firemen have produced inconsistent evidence for an increased risk of mortality from cardiovascular disease, respiratory disease, cancer and accidents. Mortality experience since 1915 has been examined in 5655 Boston firefighters, comprising all male members of the city fire department with three or more years of service. The observed cause of death as stated on the death certificates of 2470 deceased firefighters has been compared with the numbers expected based on rates for the male population of Massachusetts and of the United States of America. Among all firefighters, deaths from all causes were 91% of expected. The standardised mortality ratio (SMR) was markedly reduced (less than 50) for infectious disease, diabetes, rheumatic heart disease, chronic nephritis, blood diseases and suicide. The SMR was 86 for cardiovascular deaths, 83 for neoplastic deaths, and 93 for respiratory deaths. The SMR for accidents was 135 for active firefighters. The results suggest that the survival experience of firefighters is strongly influenced by strict entry selection procedures, ethnic derivation, and sociocultural attributes of membership. While excessive morbidity has been demonstrated in firefighters, there does not appear to be a strong association between occupation and cause-specific mortality.

Lung function in fire fighters, II: a five year follow-up fo retirees

In a study of the chronic effects of fire fighting on lung function, 1,768 employees from the Boston Fire Department were examined in 1970. From this cohort, 109 firefighters who retired in the period 1970 to 1975 have been restudied with questionnaire and ventilatory function tests. The observed vulues for pulmonary function when expressed as a per cent of predicted are consistently slightly below 100 per cent. The expected effect of cigarett smoking on lung function was demonstrated. The results suggest thetirement) are important in reducing the effect of fire fighting on subjects who may be adversely affected by the inhalation of combustion products.