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.     

Pulmonary function and respiratory symptoms in forest firefighters

This study evaluated effects on respiratory health of forest firefighters exposed to high concentrations of smoke during their work shift. This is the first study of cross-shift-respiratory effects in forest firefighters conducted on the job. Spirometric measurements and self-administered questionnaire data were collected before and after the 1992 firefighting season. Seventy-six (76) subjects were studied for cross-shift and 53 for cross-season analysis. On average, the cross-season data were collected 77.7 days after the last occupational smoke exposure. The cross-shift analysis identified significant mean individual declines in FVC, FEV₁ and FEF_25–75. The preshift to midshift decreases were 0.089 L. 0. 190 L. and 0.439 L/sec. respectively, with preshift to postshift declines of 0.065 L. 0.150 L. and 0.496L/sec. Mean individual declines for FVC, FEV₁ and FEF_25–75 of 0.033 L. 0.104 L. and 0.275 L/sec. respectively, also were noted in the cross-season analysis. The FEV₁ changed significantly (p < 0.05). The use of wood for indoor heat also was associated with the declines in FEV₁. Although annual lung function changes for a small subset (n = 10) indicated reversibility of effect, this study suggests a concern for potential adverse respiratory effects in forest firefighters. Am. J. Ind. Med. 31:503–509, 1997. © 1997 Wiley-Liss. Inc.     

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.     

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.     

A study of the acute and chronic changes in ventilatory capacity of workers in Lancashire cotton mills

Berry, G., McKerrow, C. B., Molyneux, M. K. B., Rossiter, C. E., and Tombleson, J. B. L. (1973).Brit. J. industr. Med.,30, 25-36. A study of the acute and chronic changes in ventilatory capacity of workers in Lancashire cotton mills. A prospective study of workers in 14 cotton and two man-made fibre spinning mills in Lancashire was carried out over a three-year period. A questionnaire on respiratory symptoms was completed at the start of the survey and again two years later. Up to six measurements of ventilatory capacity were made at six-monthly intervals. From these measurements the rate at which the forced expiratory volume (FEV₁) was declining (annual decline in FEV) was evaluated for 595 subjects. Six of the mills were visited on Mondays and in 199 operatives the ventilatory capacity was measured at both the beginning and end of the shift to evaluate its acute fall during work (Monday fall in FEV).

The mean annual decline in FEV for cotton workers was 54 ml/year and it was only 32 ml/year for workers in the man-made fibre mills but this lower value was attributable almost entirely to one of the two mills. For the jobs near the carding engines the annual decline was 22 ml/year higher than for speed-frame tenters. The annual decline for cigarette smokers was 19 ml/year greater than for non- and ex-smokers. The annual decline in FEV was not found to be related to symptoms of byssinosis or bronchitis, nor to present dust levels, bioactivity of the dust or air pollution, although the expected effect attributable to byssinosis turned out to be less than that which the survey was designed to detect.

The mean Monday fall in FEV was higher in cotton mills than in man-made fibre mills among those without symptoms of byssinosis and was correlated with present dust levels. For those with symptoms of byssinosis an increased Monday fall was found only in those processing coarse cotton.

For those subjects who completed the respiratory questionnaire on two occasions the chronic and acute changes in FEV were examined in relation to the change in symptoms of byssinosis. No association was found for annual decline in FEV but the Monday fall in FEV was greater for those who developed byssinosis during the survey than for those who remained free of symptoms, and was less for those who lost their symptoms than for those who retained them.

     

Day-to-day changes in ventilatory function in relation to the environment: Part I. Spirometric values

Measurements of forced expiratory volume at 1 second, forced vital capacity, and maximum midexpiratory flow have been made on four normal subjects employed in central London on each working day for five years. For three of the subjects, MMF was highest on days with low concentrations of smoke and sulphur dioxide, and it decreased at successively higher concentrations, but it was not clear whether this was an effect of pollution or of other associated factors. Respiratory infections were found to have pronounced effects on these spirometric measurements, and analysis of the results for the complete series revealed small seasonal variations and long-term changes, some of which were large and in the opposite direction from those expected with increasing age. Some immediate but transient effects of pollution on the spirometric values were seen following exercise in periods of high pollution. In addition to small direct effects, the role of pollution in affecting the course of respiratory infections and thus indirectly further affecting ventilatory function was considered.     

Pharmacological prevention of acute ventilatory capacity reduction in flax dust exposure

Valić, F., and Žuškin, E. (1973).British Journal of Industrial Medicine,30, 381-384. Pharmacological prevention of acute ventilatory capacity reduction in flax dust exposure. The protective effect of the preshift application of a bronchodilator (orciprenaline), an antihistamine drug (diadril), and ascorbic acid on flax-induced acute bronchoconstriction was studied in 13 byssinotic and 7 non-byssinotic female workers exposed to airborne fibres of biologically retted flax. Orciprenaline was applied by inhalation, while diadril and ascorbic acid were given orally. All the three drugs exerted a significant preventive effect, diminishing the acute fall of ventilatory capacity during the shift. The fall in forced expiratory volume (FEV_1·0) was reduced by 50% and the fall in maximal flow rate at 50% vital capacity (_max 50% VC) by over 65%.     

Estimation of ventilatory capacity in subjects with unacceptable lung function tests

Based on pulmonary function data collected annually for six years on 540 Vermont granite workers, FEV1 in survey 1 was estimated by extrapolating back from subsequent measurements. The extrapolation method was found to fit the observed data of subjects with reproducible initial values very well (R2 = 0.87). Extrapolated FEV1s for workers unable to perform an adequate pulmonary function test according to the standards of the American Thoracic Society were compared to extrapolated values in the rest of the cohort. After adjusting for confounding, subjects with test failure in survey 1 had a lower extrapolated FEV1 than the rest of the cohort (p = 0.07). The mean extrapolated FEV1 of the 71 workers with an initial test failure was only 95% of a predicted value derived from the group with reproducible data, and the per cent predicted decreased from 98% to 71% as the number of test failures in the follow-up surveys increased (p = 0.0004). The American Thoracic Society and the Epidemiology Standardization Project currently recommend that test failures be excluded from the analysis of epidemiological data. Our findings suggest that alternative strategies for handling non-reproducible lung function may need to be explored in order to avoid selection bias.     

Pulmonary mechanical function and diffusion capacity after deep saturation dives.

To assess the effects of deep saturation dives on pulmonary function, static and dynamic lung volumes, transfer factor for carbon monoxide (T1CO), delta-N2, and closing volume (CV) were measured before and after eight saturation dives to pressures of 3.1-4.6 MPa. The atmospheres were helium-oxygen mixtures with partial pressures of oxygen of 40-60 kPa. The durations of the dives were 14-30 days. Mean rate of decompression was 10.5-13.5 kPa/hour. A total of 43 divers were examined, six of whom took part in two dives, the others in one only. Dynamic lung volumes did not change significantly but total lung capacity (TLC) increased significantly by 4.3% and residual volume (RV) by 14.8% (p less than 0.05). CV was increased by 16.7% (p less than 0.01). The T1CO was reduced from 13.0 +/- 1.6 to 11.8 +/- 1.7 mmol/min/kPa (p less than 0.01) when corrected to a haemoglobin concentration of 146 g/l. Effective alveolar volume was unchanged. The increase in TLC and decrease in T1CO were correlated (r = -0.574, p less than 0.02). A control examination of 38 of the divers four to six weeks after the dives showed a partial normalisation of the changes. The increase in TLC, RV, and CV, and the decrease in T1CO, could be explained by a loss of pulmonary elastic tissue caused by inflammatory reactions induced by oxygen toxicity or venous gas emboli.     

Respiratory symptoms and ventilatory capacity in swine confinement workers.

A group of 59 workers (41 men and 18 women) employed in swine confinement areas was studied to assess the presence of acute and chronic respiratory symptoms and the prevalence of abnormalities in ventilatory function. A control group of 46 (31 men and 15 women) unexposed workers was studied for the prevalence of chronic respiratory symptoms. For both male and female swine confinement workers complaints of chronic cough, dyspnoea, and chest tightness were significantly more frequent than among control workers. Male workers also complained more of chronic phlegm. Male swine confinement workers who were smokers had significantly higher prevalences of chronic cough, chronic phlegm, and chronic bronchitis than male non-smoking swine confinement workers. The frequency of acute symptoms associated with the workshift was high among the swine confinement workers with more than half of the workers complaining of cough and dyspnoea associated with work. Significant acute across shift reductions in lung function occurred in swine confinement workers, being largest for FEF25. All Monday preshift ventilatory capacity measurements in male confinement workers were significantly lower than predicted values; FVC and FEV1 were found to be lower than predicted values for women. The data indicate that exposure in swine confinement buildings is associated with the development of acute and chronic respiratory symptoms and impairment of lung function. Smoking appears to aggravate these changes.     

Respiratory symptoms and ventilatory capacity in swine confinement workers.

A group of 59 workers (41 men and 18 women) employed in swine confinement areas was studied to assess the presence of acute and chronic respiratory symptoms and the prevalence of abnormalities in ventilatory function. A control group of 46 (31 men and 15 women) unexposed workers was studied for the prevalence of chronic respiratory symptoms. For both male and female swine confinement workers complaints of chronic cough, dyspnoea, and chest tightness were significantly more frequent than among control workers. Male workers also complained more of chronic phlegm. Male swine confinement workers who were smokers had significantly higher prevalences of chronic cough, chronic phlegm, and chronic bronchitis than male non-smoking swine confinement workers. The frequency of acute symptoms associated with the workshift was high among the swine confinement workers with more than half of the workers complaining of cough and dyspnoea associated with work. Significant acute across shift reductions in lung function occurred in swine confinement workers, being largest for FEF25. All Monday preshift ventilatory capacity measurements in male confinement workers were significantly lower than predicted values; FVC and FEV1 were found to be lower than predicted values for women. The data indicate that exposure in swine confinement buildings is associated with the development of acute and chronic respiratory symptoms and impairment of lung function. Smoking appears to aggravate these changes.     

Immunologic changes and pulmonary ventilatory function in animal feed processing workers]

Respiratory symptoms and immunological reactions were examined in 35 animal food workers. The most frequent positive skin prick reactions occurred to fish flour (82.9%), followed by carotene (77.1%), cornflour (65.7%), four-leaf clover (62.9%), sunflower (54.3%), chicken meat (31.4%), soy (28.6%) and yeast (22.7%). The IgE serum level was increased in 40% of the animal food workers and in 2.6% of the controls. A significantly higher prevalence of chronic respiratory symptoms was found in animal food workers than in controls. However, there was no significant difference in prevalence of chronic respiratory symptoms between workers with positive and those with negative skin tests to house dust and fish flour or between those with increased and those with normal IgE levels (except for dyspnoea). There were significant acute across-shift reductions in ventilatory capacity, particularly for FEF25. The workers with positive skin tests to fish flour demonstrated significantly larger acute FEF25 reductions than those with negative skin tests. An extract of animal food caused constriction of isolated guinea pig tracheal smooth muscle in vitro. It appears that animal food dust in addition to immunological response may produce a direct irritative effect on the airways of exposed workers.     

Day-to-day changes in ventilatory function in relation to the environment: Part II. Peak expiratory flow values

Measurements of peak expiratory flow have been made on four normal subjects on each working day for 5 years. Although there was no clear relationship between day-to-day changes in peak flow and evironmental factors, analysis of the results over the whole period showed small seasonal variations for each subject, with lower values on the colder, more polluted days in winter. A gradual increase rather than the decrease expected with age was found during the 5 years of the study. Multiple regression analyses on the combined results for the four subjects showed that after removing the trend with time the environmental factor explaining the largest proportion of the residual variance was the concentration of sulphur dioxide. The decrease in peak flow corresponding with a large increase in sulphur dioxide concentration, however, was small, and much of the day-to-day variation in peak flow was due to factors other than the concentrations of smoke or sulphur dioxide, temperature, or relative humidity. Reductions in peak flow were often associated with respiratory infections, and, as in the parallel study of spirometric measurements, the possibility that pollution had indirect effects on ventilatory function by affecting the course of respiratory infections was considered.