水泥作业工人的职业暴露和吸烟对肺通气功能和胸部X线影像的影响

目的分析职业暴露和吸烟对水泥作业工人肺通气功能和胸部X线影像的影响。方法对某市参加职业病体检的工人进行不同层次分组作回顾性研究。结果水泥厂工人不接尘组与接尘组比较，接尘组FVC％、FEV1％、FEV1％（％）低于标准值例数及胸片0^＋例数明显高于不接尘组，差异有非常显著性（P〈0．01）；而工期尘肺两者无统计学意义（P〉0．05）。水泥厂接尘工人吸烟组与不吸烟组肺通气功能与胸片的比较，吸烟组FVC％低于标准值例数明显高于不吸烟组，差异有非常显著性（P〈0．01）；吸烟组FEV1％低于标准值例数高于不吸烟组，差异有显著性（P〈0．05），FEV1％（％）低于标准值例数、胸片0^＋、Ⅰ期尘肺例数无统计学意义（P〉0．05）。结论水泥企业的职业暴露和吸烟对工人的肺通气功能影响是明显的，对X线胸部影像改变也是肯定的，肺通气功能变化比X线影像变化敏感。     

The respiratory health of carbon black workers

The respiratory health of 3,027 carbon black workers employed in 19 plants (18 Western Europe, 1 U.S.A.) was assessed by questionnaire and spirometry; chest radiographs were used to assess 935 workers in the group. The results showed that the group of workers who were exposed to carbon black dust had an increased prevalence of chronic cough, sputum production and wheezing and the mean forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV1.0) and flow between 25% and 75% of the FVC (MMEF 25-75%) were significantly less than those of the nonexposed group. Multiple regression analysis showed that the decline in respiratory health was related to the influence of smoking and age, with only a small part being associated with the combined effects of dust exposure and age. A simple type of pneumoconiosis was found in 6 of the workers, all of whom had more than 10 yr of dust exposure. Carbon black should be regarded as a nuisance dust without specific effect on the lungs.     

Respiratory illnesses and ventilatory function among workers at a cement factory in a rapidly developing country

Chronic exposure to Portland cement dust has been reported to lead to a greater prevalence of chronic respiratory symptoms and a reduction of ventilatory capacity. The seriousness of pulmonary function impairment and respiratory disease has not been consistently associated with the degree of exposure. Regular use of appropriate personal protective equipment, if available at the worksite, could protect cement workers from adverse respiratory health effects. For a variety of reasons, industrial workers in rapidly developing countries do not adequately protect themselves through personal protective equipment. This study explores the prevalence of chronic respiratory symptoms and ventilatory function among cement workers and the practice of use of personal protective equipment at work. An interviewer-administered questionnaire was used to collect information on sociodemographic characteristics, smoking profile and history of respiratory health among workers at a Portland cement plant (exposed) and workers occupationally unexposed to dust, fumes and gases (unexposed). Pulmonary function was assessed and pulmonary function impairment was calculated for the exposed and the unexposed workers. A higher percentage of the exposed workers reported recurrent and prolonged cough (30%), phlegm (25%), wheeze (8%), dyspnoea (21%), bronchitis (13%), sinusitis (27%), shortness of breath (8%) and bronchial asthma (6%). Among the unexposed, prevalences of these symptoms were 10, 5, 3, 5, 4, 11, 4 and 3%, respectively. Ventilatory function (VC, FVC, FEV(1), FEV(1)/VC, FEV(1)/FVC and PEF) was significantly lower in the exposed workers compared with unexposed workers. These differences could not be explained by age, body mass index (BMI) or pack-years smoked. Ventilatory function impairment, as measured by FEV(1)/FVC, showed that 36% of the exposed workers had some ventilatory function impairment compared with 10% of those unexposed. Certain jobs with greater exposure to cement dust had lower ventilatory function compared with others among the exposed workers. It was concluded that adverse respiratory health effects (increased frequency of respiratory symptoms and decreased ventilatory function) observed among cement workers could not be explained by age, BMI and smoking, and were probably caused by exposure to cement dust.     

Respiratory symptoms and lung function in jute processing workers: a primary investigation

This paper presents the results of an investigation of respiratory symptoms and lung function of 404 workers who had been exposed to jute dust in a jute mill. Measurement of total dust concentration and analysis of dust composition were also conducted. Most workers in the jute mill were exposed to jute dusts containing less than 5% silica, whereas a few workers were exposed to dusts containing approximately 10-15% silica. Male smokers and nonsmokers in the dust-exposed group had a higher prevalence of cough and chest tightness compared with those in the control group. Among dust-exposed workers, female nonsmokers had a significantly higher prevalence of cough, chronic bronchitis, chest tightness, and dyspnea than those in the control group. Lung function tests showed that dust-exposed workers had a greater incidence of abnormal lung function than did control workers, as measured by percentage of predicted forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1.0), and FEV1.0/FVC. Dust exposure was the main cause of respiratory symptoms and abnormal values of FEV1.0, but both cigarette smoking and dust exposure contributed to the abnormal values reported for FEV1.0.     

Epidemiologic studies of Scottish oil shale workers: II. Lung function in shale workers' pneumoconiosis

In a case control study of 122 ex-shale workers, half of whom had simple pneumoconiosis and half of whom did not, those with pneumoconiosis were found to have the poorer lung function. Significant reductions in forced expiratory capacity (FEV1), forced vital capacity (FVC), Vmax50, lung volumes, and carbon monoxide transfer were found in men with pneumoconiosis. It is suggested that these abnormalities may represent a mixture of pulmonary fibrosis and airways obstruction related to exposure to dust and fumes in shale mines and at shale retorts.     

Ventilatory function in brass workers of Gadaladeniya, Sri Lanka

A cross sectional study was conducted to determine the respiratoryhazards of brass workers. The study group was selected randomly.The control group was selected from the general population matchedfor age by cluster sampling. There was a total of 154 pairsfor the final analysis. A questionnaire was administered todetermine the prevalence of respiratory symptoms. Forced vitalcapacity (FVC), forced expiratory volume in the first second(FEV_1.0), forced expiratory flow rate in the mid 50% of theFVC(FEF_25%–75%) and peak expiratory flow rate(PEFR) weremeasured. Chest radiography was performed on those with 5 ormore years of service. Cough, phlegm, chronic bronchitis anddyspnoea were significantly higher among brass workers. Theventilatory capacity was significantly lower in all the indicatorsexcept FVC. Smoking had no significant effect and a dose responserelationship could not be demonstrated after inclusion of agein the regression model. Five point five per cent had evidenceof septal lines while 6.4% had emphysema.     

Lack of combined effects of exposure and smoking on respiratory health in aluminium potroom workers

OBJECTIVE: To investigate the combined influence on respiratory health of smoking and exposure in an aluminium potroom. METHODS: In a cross sectional study of 75 potroom workers (23 never smokers, 38 current smokers, 14 ex-smokers) and 56 controls in the same plant (watchmen, craftsmen, office workers, laboratory employees; 18 non-smokers, 21 current smokers, 17 ex-smokers), prevalences of respiratory symptoms and spirometric indices were compared. RESULTS: Smokers in the potroom group had a lower prevalence of respiratory symptoms than never smokers or ex-smokers, which was significant for wheezing (2.6% v 17.4% and 28.6% respectively, both p < 0.01), whereas respiratory symptoms in controls tended to be highest in smokers (NS). No effects of potroom work on the prevalence of respiratory symptoms could be detected. In potroom workers, impairment of lung function due to occupational exposure was found only in non-smokers, with lower results for forced vital capacity (FVC) (98.8% predicted), forced expiratory volume in one second (FEV1) (96.1% predicted) and peak expiratory flow (PEF) (80.2% predicted) compared with controls (114.2, 109.9, and 105.9% predicted; each p < 0.001). Conversely, effects of smoking on lung function were only detectable in non-exposed controls (current smokers v non-smokers: FVC 98.8% v 114.2% predicted; p < 0.01; FEV1 95.5 v 109.9% predicted; p < 0.05). CONCLUSIONS: In a cross sectional survey such as this, the effects of both smoking and occupational exposure on respiratory health may be masked in subjects with both risk factors. This is probably due to strong selection processes which result in least susceptible subjects continuing to smoke and working in an atmosphere with respiratory irritants.

 

     

Decline in annual lung function in workers exposed to asbestos with and without pre-existing fibrotic changes on chest radiography.

OBJECTIVES--To examine whether or not workers with pre-existing mild pulmonary fibrosis have accelerated decline in forced expiratory volume in one second (FEV1) or forced vital capacity (FVC), under low level exposure to chrysotile asbestos. METHODS--All male workers in two asbestos manufacturing factories were followed up annually for six years to compare their declines in FEV1 and FVC. The values of FEV1 and FVC were divided by the square of the person's height to adjust for body size differences (FEV1/Ht2 and FVC/Ht2, respectively). Annual change was calculated for each subject as a slope of the simple linear regression with FEV1/Ht2 or FVC/Ht2 regressed according to age. Analysis was conducted on 242 middle aged workers who had normal routine spirometry values, normal chest radiographs or mild pneumoconiosis up to 1/2 grade, without changes either in smoking habit or severity of pneumoconiosis during the study period, and with acceptable spirograms in three or more surveys. The occupational environment, in terms of chrysotile asbestos, had been well controlled below the threshold limit value of Japan at that time--namely, 2 fibres/micromilligrams. RESULTS-There was no significant effect from the interaction between pre-existing mild pulmonary fibrosis and low level of exposure to chrysotile asbestos on the accelerated annual decline of FEV1/Ht2, or FVC/Ht2. Fibrosis significantly contributed to annual changes in FEV1/Ht2, even after adjustment for mean FEV1 and smoking. The point estimate of the contribution was - 4.9 ml/m2/y. No significant independent contribution of exposure was found in decline of either FEV1/Ht2 or FVC/Ht2. CONCLUSIONS--Pre-existing pulmonary fibrosis is an independent risk factor for accelerated annual decline of FEV1, even when mild and stable. Additional decline due to exposure to chrysotile asbestos is less probable if it is well controlled under the current threshold limit value.     

Byssinosis in Guangzhou, China.

OBJECTIVES--To study the prevalence of byssinosis and other respiratory abnormalities in workers exposed to cotton dust in Guangzhou in two factories that processed purely cotton. METHODS--All the 1320 workers exposed were included. The controls were 1306 workers with no history of occupational dust exposure. Total dust and inhalable dust were measured by Chinese total dust sampler and American vertical elutriator respectively. A World Health Organisation questionnaire was used. Forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were measured by a Vitalograph spirometer. RESULTS--The median inhalable dust concentrations ranged from 0.41 to 1.51 mg/m3 and median total dust concentrations from 3.04 to 12.32 mg/m3. The prevalence of respiratory abnormalities in the cotton workers were (a) typical Monday symptoms 9.0%; (b) FEV1 fall by > or = 5% after a shift 16.8%; (c) FEV1 fall by > or = 10% after a shift 4.2%; (d) FEV1 < 80% predicted 6.1%; (e) FEV1/FVC < 75% 4.0%; (f) cough or phlegm 18.2%; (g) chronic bronchitis 10.9%; and (h) byssinosis, defined by (a) plus (b) 1.7%. With the exception of (d), most of the prevalences increased with increasing age, duration of exposure, and cumulative inhalable dust exposure. No increasing trends of respiratory abnormalities were found for current total dust, inhalable dust, and cumulative total dust concentrations. Compared with controls, after adjustment for sex and smoking, with the exception of (d), all the pooled relative risks of respiratory abnormalities were raised for cotton exposure. CONCLUSION--It is concluded that cumulative inhalable cotton is likely to be the cause of byssinotic symptoms, acute lung function decrements, cough, or phlegm, and chronic bronchitis.     

Cement dust exposure and ventilatory function impairment: an exposure-response study

We investigated cumulative total cement dust exposure and ventilatory function impairment at a Portland cement factory in Tanzania. All 126 production workers were exposed. The control group comprised all 88 maintenance workers and 32 randomly chosen office workers. Exposed workers had significantly lower forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), peak expiratory flow rate (PEF), FEV1/FVC, FVC%, FEV1% and PEF%, than controls adjusted for age, duration of employment, height, and pack-years. Cumulative total dust exposure was significantly associated with reduced FVC, forced expiratory volume in 1 second, and peak expiratory flow rate adjusted for age, height and pack-years. Cumulative total dust exposure more than 300 mg/m year versus lower than 100 mg/m years was significantly associated with increased risk of developing airflow limitation (odds ratio = 9.9). The current occupational exposure limit for total cement dust (10 mg/m) appears to be too high to prevent respiratory health effects among cement workers.     

Respiratory symptoms and lung function in a group of solderers.

A total of 1611 women working in a large electronics company were interviewed using a modified version of the Medical Research Council's questionnaire on respiratory symptoms, and their lung function was tested using a Vitalograph dry wedge spirometer. When the prevalence of symptoms was compared using the chi 2 test among four occupational groups--namely, solderers, ex-solderers, non-solderers, and office workers--few significant differences were found. The group of ex-solderers tended to have a greater prevalence of symptoms than the other three groups. Forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were measured, and when these were compared for smokers, the office workers were found to have a greater mean age adjusted FVC and FEV1 than the three other groups. The pattern was less distinct for non-smokers. When duration of exposure to solder fumes was allowed for, differences in lung function were more suggestive of being related to smoking habit than occupational exposure to solder fumes.     

Obstructive pulmonary function defects among Taiwanese firebrick workers in a 2-year follow-up study.

The purpose of the study was to follow up an earlier observation of pulmonary function among workers employed in firebrick-manufacturing factories. A 2-year follow-up study of pulmonary function among 442 workers in 30 firebrick-manufacturing factories was designed. Excluding 79 workers with a history of other occupational dust exposure, changes in pulmonary function of 291 firebrick workers were compared with pulmonary function in 72 control subjects over a period of 2 years. Baseline pulmonary function values (i.e., forced expiratory volume in 1 second [FEV1]/forced vital capacity [FVC] and forced expiratory flow after 50% of vital capacity has been expelled [FEF50%] in smoking firebrick workers, and FEV1/FVC and FEF75% in nonsmoking firebrick workers) were significantly lower than those in the comparison group. The statistical method for repeated measurements was used for comparison of the difference between follow-up and baseline lung function. There was no significant difference in FVC and FEV1 changes between firebrick workers and those in the comparison group during the 2-year follow-up period. The decreases in FEV1/FVC, peak expiratory flow rate, maximal midexpiratory flow, and FEF50% in the firebrick workers were significantly greater than in the comparison group, after adjustment for smoking status. The FEV1, maximal midexpiratory flow, FEF50%, and FEF75% also showed a dose-response relationship with job titles. The decrement of pulmonary function in the 2-year follow-up period was the worst in burning work, followed by crushing and molding. The results show that workers in firebrick-manufacturing factories with exposure to silica-containing dusts may contract obstructive pulmonary function defects.     

Follow-up study on pulmonary function of dust workers: an epidemiological evaluation of discontinued workers of dust operations

An epidemiologic study on 176 dust workers from various facilities was initiated in 1978. Their mean age was 48.3 years and mean duration of employment was 21.6 years. No workers complained of chronic cough and phlegm. Their chest X-rays were found to belong to Category I of the diagnostic criteria for pneumoconiosis in Japan. Pulmonary function test was performed on these workers, however, 54 workers discontinued taking part in the study by the end of 1979, and 49 workers had discontinued by 1981. A total of 73 workers had a five-year follow-up survey of pulmonary function. Forced expiratory volume in one second divided by forced vital capacity (FEV1.0/FVC) and forced expiratory flow rate at 25% of FVC divided by height (V25/H) were mainly compared by smoking habit, work years, type of job, size of company, and the time when they discontinued their jobs. Predicted percentage values of lung function were used for the adjustment of the influence of workers' ages. Decrement of FEV1.0/FVC and V25/H in the five-year follow-up group were larger than the screening level. The mean values of those functional parameters in the early discontinued group were lower than late discontinued and active working groups. The active working group was considered to be a physically healthy workers' population.     

职业暴露和吸烟对焦炉工肺通气功能的影响

目的　研究职业暴露和吸烟对焦炉作业工人肺通气功能的影响。方法　对某焦化厂各炉炉顶、炉侧以及炉底进行环境有害物的监测;对2 34名焦炉作业工人进行吸烟指数的调查和肺通气功能测定。结果　焦炉作业环境有害物浓度呈炉顶>炉侧>炉底的趋势;吸烟的焦炉作业工人标化第一秒最大呼气量(FEV1,90 .8%±8.6 % )与第一秒最大呼气率(FEV1% ,95 .4 %±12 .4 % )均明显低于不吸烟组(10 0 .9%±14 .3%、10 8.9%±17.6 % ) ;吸烟的焦炉作业工人的标化最大肺活量(FVC)与职业接触苯溶物、苯并[a]芘和吸烟指数的偏相关系数分别为- 0 .2 4 9、- 0 .187和- 0 .36 8,FEV1与三者的偏相关系数分别为- 0 .2 5 5、- 0 .191和- 0 .388,FEV1%与三者的偏相关系数分别为- 0 .131、- 0 .10 7和- 0 .0 6 5 ;不吸烟的焦炉作业工人的FVC、FEV1和FEV1%与职业接触苯溶物的偏相关系数分别为- 0 .15 4、- 0 .0 5 2和- 0 .176 ,与苯并[a]芘的偏相关系数分别为- 0 .12 1、- 0 .0 37和- 0 .15 9。结论　焦炉作业工人肺通气功能与职业接触和吸烟指数均有一定的负相关。     

Interactive effect of paraoxonase-1 Q192R polymorphism and smoking history on the lung function decline in grain workers

PURPOSE: This retrospective longitudinal study investigated the association between the Q192R polymorphism of the high-density lipoprotein-associated multifunctional antioxidant enzyme, paraoxonase-1 (PON1), and lung function decline, while taking into account smoking history. METHODS: The demographic, occupational, and respiratory symptom information and lung function variables were obtained from 216 male Saskatchewan grain workers. RESULTS: An interaction between the PON1 genotypes and smoking status was observed. Current smokers with the 192R allele had a lower forced expiratory volume in the first second (FEV(1)) and FEV(1) per forced vital capacity (FVC). The annual decline rate of FEV(1)/FVC in current smokers was greater among 192R allele carriers than noncarriers (0.58+/-0.05 vs. 0.35+/-0.04 %/yr, p<0.0001). A similar result was observed with FEV(1) (40.9+/-6.4 vs. -33.0+/-7.0 mL/yr, p=0.10). The annual decline rate of FVC was not influenced by the genotypes. CONCLUSIONS: These results strengthened the previous findings of our cross-sectional study, suggesting that the 192R allele may be a novel genetic risk factor for airway injury among current smokers.     

Lung function among asbestos cement factory workers: cross-sectional and longitudinal study

Ventilatory capacity tests and standardized respiratory questionnaires were used in 1973 and in 1980 to measure the effect of mixed dust exposure in the asbestos cement industry on respiratory symptoms and lung function in 65 exposed workers and 30 controls (exposed to polyvinyl chloride but not to asbestos). Workers exposed to asbestos had 1) a higher prevalence of breathlessness and chest pain, and a higher incidence of breathlessness; 2) lower 1980 values of forced vital capacity (FVC) (0.27-0.83 liters) and forced expiratory volume in 1 sec (FEV1) (0.23-0.62 liters); and 3) a faster decline (nearly 40 ml/year) in FVC and FEV1 between 1973 and 1980. The FVC annual decrease was 52.5 ml in the subjects with more than 15 years since first asbestos exposure, whereas it was 24.3 ml in those with less than 15 years, suggesting a faster decline after 15 years of exposure. The effect of asbestos exposure and smoking habits was less than additive as regards pulmonary function.     

Chronic bronchitis, work related respiratory symptoms, and pulmonary function in welders in New Zealand

OBJECTIVES: A cross sectional study of respiratory symptoms and lung function in welders was performed at eight New Zealand welding sites: 62 current welders and 75 non-welders participated. METHODS: A questionnaire was administered to record demographic data, smoking habit, and current respiratory symptoms. Current and previous welding exposures were recorded to calculate a total lifetime welding fume exposure index. Forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and peak expiratory flow (PEF) were measured before the start of the shift. RESULTS: There were no significant differences in ethnicity, smoking habits, or years of work experience between welders and non-welders. Symptoms of chronic bronchitis were more common in current welders (11.3%) than in non-welders (5.0%). Of those workers with a cumulative exposure index to welding fume > or = 10 years, 16.7% reported symptoms of chronic bronchitis compared with 4.7% of those with a cumulative exposure index < 4 years (odds ratio (OR) 4.1, 95% confidence interval (95% CI) 0.90 to 17.6). Workers with chronic bronchitis had significantly lower measures of baseline PEF (p = 0.008) and FEV/FVC ratio (p = 0.001) than workers without chronic bronchitis. Multivariate analysis showed that current smoking (OR 9.3, 1.0 to 86.9) and total exposure index to welding fumes > 10 years (OR 9.5, 1.3 to 71.9) were independent risk factors for chronic bronchitis. The report of any work related respiratory symptom was more prevalent in welders (30.7%) than non-welders (15.0%) and workers with these symptoms had significantly lower FEV, (p = 0.004) and FVC (p = 0.04) values. Multivariate analysis identified a high proportion of time spent welding in confined spaces as the main risk factor for reporting these symptoms (OR 2.8, 1.0 to 8.3). CONCLUSION: This study has documented a high prevalence of symptoms of chronic bronchitis and other work related respiratory symptoms in current welders. Also, workers with chronic bronchitis had reduced PEF and FEV/FVC compared with those without chronic bronchitis. These symptoms related both to cigarette smoking and a measure of lifetime exposure to welding fume.

 

     

煤矿工人与煤工尘肺患者氧化应激水平比较

目的 探讨血清氧化应激指标用于煤尘致肺早期损伤监测和煤工尘肺病况判断的可行性.方法 选取某煤矿64名煤矿工人(掘进工34人作为煤尘高暴露组,采煤工13人作为中暴露组,辅助工17人作为对照组)、45例煤工尘肺患者(Ⅰ期23例,Ⅱ期19例,Ⅲ期3例).检测血清超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、丙二醛(MDA)的水平及肺活量(VC)、用力肺活量(FVC)、第1秒用力呼气容积(FEVI)、第1秒呼气容积占用力肺活量的百分比(FEV1/FCV%).结果 与辅助工比较,掘进工、采煤工血清SOD、CAT、MDA水平及VC、FVC、FEV1和FEVI/FCV的差异均无统计学意义;与煤矿工人比较,Ⅰ期、Ⅱ期煤工尘肺患者血清CAT减少(P＜0.01,P＜0.01);Ⅰ期煤工尘肺患者VC、FEV1、FEV1/FVC、Ⅱ期煤工尘肺患者VC、FEV1及Ⅲ期煤工尘肺患者FEV1均降低(P＜0.05,P＜0.01,P＜0.05,P＜0.05,P＜0.01,P＜0.05).Spearman秩相关分析显示,血清CAT、SOD水平与VC、FVC、FEV1均呈正相关(n=109,P＜0.05).结论 血清CAT、SOD有可能作为煤尘致肺损伤监测的辅助指标和煤工尘肺病况判断的参考指标,但能否应用于煤尘致肺早期损伤监测,尚不能给出肯定的结论.     

Respiratory symptoms and lung function in a sample of Vermont dairymen and industrial workers.

This study reviews the respiratory status of a sample of Vermont male dairy farmers, and a comparison group from industry, matched for age, sex and smoking. Survey instruments included a standardized questionnaire and simple pulmonary function tests. In general, past and present smokers had more respiratory symptoms than never-smokers; and farmers, in all smoking categories, reported symptoms with greater frequency than did their counterparts from industry. Forced vital capacity (FVC) tended to be lower among men with a history of smoking but, within each smoking category, dairymen and factory workers had very similar FVCs. Farmers who had never smoked or who were current cigarette users had lower FEV1/FVC (forced expiratory volume at one second/forced vital capacity) ratios than their controls from industry. Sixteen diarymen demonstrated precipitins to either Micropolyspora faeni (13) or Thermoactinomyces vulgaris, (3), but only one reported a constellation of symptoms compatible with farmer's lung disease. The estimated prevalence of antibodies to thermophilic actinomyces in this farm population was approximately 10 per cent. Although sample sizes were limited, dairymen from small farms tended to be older, have more respiratory symptoms, less satisfactory pulmonary function, and more serologic evidence of exposure to farmer's lung antigens than their counterparts from large farms.     

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.