Occupational asthma due to spruce wood

Workers exposed to a variety of wood dusts are known to experience work-related respiratory symptoms, including occupational asthma. There are, however, few reports of occupational asthma due to spruce wood. We present the case of a 31-year-old sawmill owner with severe asthma caused by exposure to spruce wood dust, who developed asthmatic symptoms after 2 years of working. Investigations included clinical examination, routine laboratory tests, spirometry, chest X-ray, total serum immunoglobulin E (IgE) and specific serum IgEs against various woods and other occupational allergens. Additionally, we monitored the peak expiratory flow rate (PEFR) and symptom score both at work and when off work. Specific serum IgE for spruce wood was detected (7.8 IU/ml). The results of PEFR and workplace symptom-score monitoring, coupled with an elevated eosinophil count in induced sputum, supported the diagnosis of occupational asthma. To our knowledge, this is the first well-documented case of occupational asthma induced by spruce wood dust. A type I immunological mechanism seems to be responsible.     

Risk factors associated with airway allergic diseases from exposure to laboratory animal allergens among veterinarians

Objectives Investigate the risk factors for the development of occupational airway allergy (OAA) from exposure to laboratory animal allergens (LAA) among Polish veterinarians. Methods Two hundred veterinarians responded to the questionnaire and were subjected to skin prick test (SPT) to common allergens and LAA (rat, mouse, hamster, guinea pig, rabbit). Evaluation of total serum IgE level and specific IgE against occupational allergens was performed. In addition, bronchial hyperreactivity (BHR) and peak expiratory flow rate (PEFR) were measured before and after specific challenge testing (SCT) only in the subjects with work-related symptoms suggestive of occupational asthma (OA). Results The prevalence of asthmatic and ocular symptoms was statistically more prevalent in the group of veterinarians sensitised to LAA versus non-sensitised subjects. The most frequent occupational allergens of skin and serum reactivity were LAA (44.5 and 31.5%, respectively). In 41 (20.5%) and in 22 (11%) subjects out of 200 veterinarians, serum specific IgE to natural rubber latex (NRL) allergens and disinfectants was also found. Serum sensitisation to cat allergens and daily contact with laboratory animals (LA) increased the risk for developing isolated occupational rhinitis. Furthermore, working time of more than 10 years and daily contact with LA were also significant risk factors for the development of OAA. Measuring PEFR and BHR before and after SCT is a useful method to confirm the presence of OA. Conclusions Allergy to LAA is an important health problem among veterinary medicine practitioners in Poland.     

Toxic encephalopathy due to 1,1,1-trichloroethane exposure

Immunological status and respiratory function were studied in a group of 64 wool textile workers (52 women and 12 men). A group of 46 workers not exposed to wool dust served as a control for the respiratory symptoms and immunologic testing. Skin testing was performed with different wool allergens (domestic and Australian) as well as with common allergens. Ventilatory capacity was measured in wool workers on Mondays before and after the work shift. The prevalence of positive skin tests to all allergens was higher in wool than in control workers, although the difference was statistically significant only for washed domestic wool (wool workers: 42.2%; control workers: 19.6%; p < 0.05). Increased serum IgE levels were more frequent in wool (26.6%) than in control workers (3.1%) (p<0.01). In wool textile workers there was a high prevalence of acute and chronic respiratory symptoms. Significant across-shift reductions in ventilatory capacity tests, as well as abnormal baseline lung function, were recorded in wool textile workers. Individual data demonstrated that many of the wool workers had FEF₂₅ lower than 70% of predicted. In general, the prevalence of symptoms and the lung function abnormalities did not correlate with the results of specific (wool) skin tests. Our data indicate that exposure to wool dust in some workers may be associated with the development of acute and chronic respiratory symptoms and impairment of lung function. Immunologic abnormalities, although frequent in this group, do not appear to be associated with the severity of these changes.     

Occupational asthma from inhaled egg protein

We evaluated workers and performed an industrial hygiene assessment at a plant where raw eggs are processed into powdered egg yolk and whole egg. Egg dust levels in the packaging room straddled the American Conference of Governmental Industrial Hygienists' (ACGIH) exposure guideline of 10 mg/m3 for nuisance dust. We obtained medical histories from 25 workers, and performed physical examinations, spirometry, and serial determinations of peak expiratory flow rate (PEFR) by portable meter every 3 hrs (while awake) for 7 days. We defined symptomatic bronchial lability to be a decrement in PEFR on any one day of 20% or more of the day's maximum, with concurrent symptoms. Skin-prick tests and serum assays for specific IgE by the radioallergosorbent (RAST) method were performed to assess sensitivity to commercial egg proteins, egg protein fractions, and freshly prepared extracts of whole egg powder and yolk. We classified participants as definite cases of asthma if both the examining physician diagnosed asthma and symptomatic bronchial lability was demonstrated by serial PEFR determinations. Definite noncases of asthma were those participants in whom the physician did not diagnose asthma and in whom symptomatic bronchial lability was not demonstrated by PEFR. All five definite cases, compared to three of 16 definite noncases of asthma, had one or more positive skin-prick tests to egg proteins. Four of five cases, compared to 0 of 14 noncases, who had serum determinations, had an elevated RAST to one or more of the egg proteins. This study demonstrates that occupational asthma associated with IgE-mediated allergy to egg proteins occurs among workers exposed to inhaled egg proteins.     

The possible role of cockroaches in baker's asthma

BACKGROUND: Baker's asthma is related to wheat flour exposure and to other cereal dust exposure. OBJECTIVES: The cockroach is considered a significant allergen and can occasionally trigger asthma in bakery workers. METHODS: The case of a 33-year-old male, suffering from asthma in the workplace with previous equivocal tests for cereal dust was investigated Clinical assessment of the worker consisted of cutaneous and blood screening for common and occupational allergens, including cockroach. The subject was monitored for aspecific bronchial reactivity and peak flow in a cockroach disinfected workplace, and these data were compared to data obtained after previous workplace exposure. RESULTS: The worker was not allergic to wheat and other cereal dusts or alpha-amylase, but was sensitized to cockroach. His asthmatic symptoms disappeared, and bronchial reactivity varied after a long period outside the bakery workplace. PEF monitoring, that had showed diurnal variability > 20% and differences between working and non-working periods, demonstrated both normal values and daily variations less than 10% when he returned to the cockroach disinfected workplace. CONCLUSIONS: The cockroach is a common allergen, however no case of work-related baker's asthma due to the cockroach has been previously described. Clinical history and analysis of the allergens at the workplace must direct the clinical approach of the investigators, in order to correctly evaluate the subject and enable him/her to resume work.     

Bronchial hyperresponsiveness in women cooks and cleaners

The aim of this cross-sectional study was to assess the prevalence and characteristics of bronchial hyperresponsiveness (BHR) in 43 women cleaners (aged 26 to 57) and 37 women cooks (aged 29 to 55) and compare them with 45 controls (women office workers aged 27 to 58). The evaluation of all subjects included a questionnaire, skin prick tests to common aeroallergens, spirometry, and histamine challenge (PC20 < or = 8 mg mL(-1)). We found higher BHR prevalence in cleaners and cooks than in office workers (30.2 % and 29.7 %, vs. 17.7 %, respectively), but statistical significance was not reached. The prevalence of mild and moderate to severe BHR was similar in all groups. Borderline BHR prevalence was significantly higher in cleaners than in controls (16.2 % vs. 6.6 %, P=0.032) whereas the difference was on the verge of significance in cooks (13.5 % vs. 6.6 %, P=0.081). Moderate to severe BHR was strongly associated with positive family history of asthma and atopy in all groups. Mild BHR was significantly associated with daily smoking in cleaners (P=0.031) and cooks (P=0.021), as well as with the duration of exposure in cleaners (P=0.038). Borderline BHR was closely related to daily smoking and duration of exposure in both cleaners and cooks. Our findings indicate an important role of workplace exposure in borderline BHR development, as well as the significant effect of smoking on mild BHR development in women cleaners and cooks.     

Respiratory function and immunological status in cocoa and flour processing workers

Respiratory function and immunological status were studied in 40 cocoa and 53 flour processing workers employed as packers in a confectionry industry and in 65 unexposed control workers in the same industry. A high prevalence of chronic respiratory symptoms was recorded in exposed workers, varying from 5.0% to 30.0% in cocoa workers and from 5.7% to 28.3% in flour workers. Occupational asthma was diagnosed in 2 (5%) of the cocoa workers and in 3 (5.7%) of the flour workers. None of the control workers suffered from occupational asthma. The prevalence of almost all chronic respiratory symptoms was significantly greater in cocoa and flour workers than in control workers. There was also a high prevalence of acute symptoms that developed during the work shift, being highest for cough (cocoa: 57.5%; flour: 50.9%) and eye irritation (cocoa: 50.0%; flour: 54.7%). Significant across-shift reductions of ventilatory capacity were recorded in exposed workers, being largest for flow rates at 50% and the last 25% of the vital capacity on maximum expiratory flow-volume (MEFV) curves (FEF₅₀, FEF₇₅). The prevalence of positive skin tests for cocoa (60.2%) was significantly higher than the prevalence of positive skin tests for flour (25.8%) among the 93 exposed workers (p < 0.05). Control workers had significantly lower prevalences of positive skin tests to cocoa (4.6%) and flour (12.3%) than exposed workers (p < 0.01). Increased total serum IgE levels were found in 17.5% of cocoa and in 18.7% of flour workers; none of the control workers had increased IgE levels. Bronchoprovocation testing demonstrated significant decreases in lung function following inhalation of cocoa dust extract and flour dust in workers with respiratory symptoms and large across-shift reductions in lung function. Dust concentrations in the working environment were higher than those recommended by Croatian standards. These data suggest that workers employed in the processing of cocoa and flour may be at a high risk for the development of allergic sensitization and respiratory impairment. Am. J. Ind. Med. 33:24–32, 1998 © 1998 Wiley-Liss, Inc.     

Exercise-induced bronchoconstriction in textile and agricultural workers and in bakers

To assess the prevalence and the characteristics of exercise-induced bronchoconstriction (EIB) in subjects occupationally exposed to organic dusts we performed a cross-sectional study including 152 exposed subjects (67 textile workers, 42 agricultural workers, and 43 bakers) and 72 unexposed controls. Evaluation of exposed and unexposed subjects included a questionnaire, skin prick tests to common inhalant allergens, spirometry, and exercise challenge tests (ECT). The EIB prevalence found in textile workers was 8.9 %, in agricultural workers 7.1 %, in bakers 6.9 %, and in office workers 5.5 %. The highest bronchial reaction to exercise was found in ECT-positive agricultural workers (26.1+/-6.9), followed by textile workers (25.2+/-7.4), bakers (23.0+/-5.8), and office workers (21.8+/-4.4). EIB was significantly associated with atopy and positive family history of asthma in all exposed groups. EIB was significantly associated with smoking duration in textile workers (P=0.039) and agricultural workers (P=0.027). Bronchial reaction to exercise was significantly greater in smoking than in non-smoking textile (P=0.045) and agricultural workers (P=0.032). Our data suggest that the combination of daily smoking and workplace exposure to certain types of organic dusts could contribute to EIB development and severity.     

Occupational asthma in New Zealanders: a population based study.

OBJECTIVES: To examine the effect of occupation on respiratory symptoms in a randomly selected adult population aged 20-44 years. METHODS: It is based on the phase II sampling of the New Zealand part of the European Community respiratory health survey. 1609 people (63.9% response rate) completed a detailed respiratory questionnaire. Of those responding, 1174 (73%) underwent skin tests and 1126 (70%) attended to undergo methacholine bronchial challenge. Current occupation was recorded and a previous occupation was also recorded if it had led to respiratory problems. 21 occupational groups were used for analysis for the five definitions of asthma wheezing in the previous 12 months; symptoms related to asthma; bronchial hyperresponsiveness (BHR); BHR with wheezing in the previous 12 months; and BHR with symptoms related to asthma. RESULTS: Prevalence odds ratios (ORs) were significantly increased for farmers and farm workers (OR 4.16, 95% confidence interval (95% CI) 1.33 to 13.1 for the combination of wheezing and BHR). Increased risks of prevalence of asthma were also found for laboratory technicians, food processors (other than bakers), chemical workers, and plastic and rubber workers. Workers had also been divided into high and low risk exposure categories according to relevant publications. The prevalence of wheezing was greater in the high risk group (OR 1.57, 95% CI 0.83 to 2.95) than in the low risk group. Atopy was associated with asthma, but the prevalence of atopy did not differ significantly between occupational exposure groups. The attributable risk of wheezing that occurred after the age of 15 years and that was estimated to be due to occupational exposure (based on the defined high risk group) was 1.9%, but this increased to 3.1% when farmers and food processors (other than bakers) were also included in the high risk group. CONCLUSIONS: This population based study has identified certain occupations significantly associated with combinations of asthmatic symptoms and BHR.     

Exercise-induced bronchoconstriction and exercise-induced respiratory symptoms in workers exposed to tea dust

Assuming that airborne particles and pollutants are important contributing factors in the development of exercise-induced bronchoconstriction (EIB), we performed a case-control study including 63 tea workers (36 men and 27 women, aged 36-55, duration of employment 3-30 years) and an equal number of office workers, matched by sex and age. Exercise-induced respiratory symptoms were recorded in a questionnaire. Skin prick tests, spirometry, as well as exercise and histamine challenge were carried out. Environmental measurements were performed on site during the work shifts. The prevalence of self-reported exercise-induced respiratory symptoms and EIB did not differ significantly between the exposed and control group (41.6% vs 36.8%, and 6.4% vs 4.8%, respectively). In both exposed and control workers, EIB was strongly linked to asthma (P < 0.01). In the exposed workers it was significantly associated with positive family history of asthma (P < 0.01) and positive family history of atopies (P < 0.05), whereas in the exposed smokers it was significantly related to smoking duration (P < 0.05). Bronchial reaction to exercise in the exposed smokers was significantly greater than in control smokers (P < 0.05). Self-reported exercise-induced respiratory symptoms were weakly associated with EIB, with a large proportion of false positive and a low proportion of false negative results in both groups.     

Sensitization to green coffee bean (GCB) and castor bean (CB) allergens among dock workers

Summary Dock workers (n = 218) occupationally exposed to green coffee beans (GCB) were studied, using a specific questionnaire for allergic symptoms and skin tests for common and occupational allergens. Thirty-one workers (14.3%) complained of allergic symptoms of the eye, nose and bronchial system at the workplace. The prick tests, using both commercial allergens and specific extracts prepared from the most common types of coffee and their corresponding sacks, confirmed a sensitization in 21 workers (9.6%). A positive skin reaction to castor beans (CB) was found in nearly all these cases; in ten workers there was also a positive reaction to GCB allergens and in 14 cases prick tests were positive to extracts of sacks. There was a good concordance between prick tests and specific IgE for CB (95.0%) and also, but to a lesser extent, for GCB. The authors concluded that there is a significant risk of sensitization to CB and GCB allergens in dock workers occupied in handling green coffee bean, despite the fact that the exposure is not continuous. CB emerged as a common contaminant of GCB from various countries. For effective prevention, a modification of the methods of transport is required to avoid CB contamination to other products. Eliminating environmental dust during shipping operations is the most important preventive measure and it can be achieved by the use of containers, as some exporting countries are already doing.     

Cork workers’ occupational asthma: lack of association with allergic sensitisation to fungi of the work environment

Objectives To evaluate allergic sensitisation to Chrysonilia sitophila, Penicillium glabrum, and Trichoderma longibrachiatum in cork workers with asthma.Methods Skin prick tests with a battery of common allergens and with the three fungi were performed on ten cork workers with asthma and eight non-exposed asthmatics. Based on serial peak expiratory flow measurements, five were classified as having occupational asthma (AO) and five as having non-occupational asthma (NOA). In exposed patients, specific antibodies for the three fungi were also studied by immunoblottingResults Two out of ten patients with occupational exposure and four out of eight of the control group showed positive results for skin prick tests for common allergens. Moreover, two out of five patients with OA and three out of eight controls exhibited sensitisation to storage mites. All exposed patients (with OA or NOA) had negative skin prick test results for the fungal extracts. In patients with asthma and occupational exposure, immunoblotting results confirmed the absence of specific IgE. However, specific IgG4 was present in some cases.Conclusions Atopy does not seem to characterise occupational asthma in cork workers. Despite their long exposure to moulds, we could not find evidence of IgE sensitisation to the three most prevalent cork fungi in patients with OA, which points to the search for other causative agents, such as cork chemical compounds or contaminants.     

Work-related asthma in automobile spray painters: two case reports

This report describes two patients who had developed asthma after working as automobile painters with isocyanate-based aerosol paint for two years or over. In both patients asthma was confirmed using the standard diagnostic procedure. One of the subjects was atopic. One was ex-smoker and the other had never smoked. Neither had a family history of asthma. The symptoms occurred after workplace exposure lasting two years in one patient and three in the other. As both reported work-relatedness of the symptoms, they underwent serial peak expiratory flow rate (PEFR) measurement and bronchoprovocation testing. Significant work-related changes in PEFR diurnal variations and in non-specific bronchial hyperresponsiveness (NSBH) were observed in one patient, suggesting allergic occupational asthma (OA), while the other patient was diagnosed work-exacerbated asthma (WEA). Our data confirm that spray painting is an occupation with increased risk of respiratory impairment and asthma.     

Prevalence and host determinants of occupational bronchial asthma in animal shelter workers

Objective We examined the risk factors for the development of airway allergy in animal shelter workers. Methods The study population comprised 88 animal shelter workers occupationally exposed to cats and dogs. They responded to a questionnaire concerning the history of exposure to animal allergens and job characteristics and were subjected to skin prick test (SPT) to common and occupational allergens (cat and dog), and determination of total serum IgE level and specific IgE. In addition, SPT with rat and mouse allergens were performed. Bronchial hyperreactivity and peak expiratory flow rate were measured at work and off work only in workers with work-related symptoms suggestive of occupational asthma (OA). Results The prevalence of OA was 9.1%. Sensitization to dog allergens was higher than to cats. The multivariate logistic regression analysis revealed a significant role of positive family history of atopy and having a dog as pet in the past for the development of occupational airway allergy (OR 5.9; 95% CI 1.76, 20.00; P = 0.003; OR 6.47; 95% CI 1.90, 22.02; P = 0.002, respectively). In the multivariate logistic regression analysis, the risk for developing OA was most clearly associated with growing up in the country (OR 7.59; 95% CI 1.25, 45.9; P = 0.025). Conclusions Allergic disease is a serious occupational health concern for subjects who have occupational contact with cats and dogs.     

The influence of workplace environment on lung function of flour mill workers in Jalgaon urban center

The workplace environment affects the health of workers. Unhygienic conditions are observed in the workplace environment of flour mills as fine organic flour dust gets airborne in the indoor environment of the flour mills. The present work was undertaken to study the health problems related to the workplace environment of flour mill workers. The results show that flour mill workers are receiving a heavy dose (average exposure concentration, 624 microg/m3) of flour dust. To determine the impact of flour dust on the lung function of the workers spirometric analysis was conducted. Significant declines in forced vital capacity (FVC), peak expiratory flow rate (PEFR) and forced expiratory volume in one second (FEV1) were observed in the flour mill workers as compared to expected values. This study reveals reduced lung efficiency of flour mill workers due to excessive exposure to fine organic dust prevalent in the workplace environment. The impairment in lung efficiency was increased with duration of exposure in the flour mill workers. The analysis of questionnaires used to generate information on self-reported problems reveals that most of the workers were suffering from asthma and respiratory problems. Furthermore, the data shows that 42% of the flour mill workers were having shortness of breath problems, 34% of workers were having frequent coughing, and 19% workers were having respiratory tract irritation. We recommend the compulsory use of personal protective equipment (nose mask) by flour mill workers during working hours. This would help to protect the workers health from the flour dust prevalent in the workplace environment. A regular periodic examination is necessary to measure the impact of particulate matter on the health of the flour mill workers.     

Diurnal variation in peak expiratory flow rate among grain elevator workers

The diurnal variation (DV) in peak expiratory flow rate (PEFR) has been studied among 132 grain elevator workers who accomplished three daily measurements of PEFR during three weeks. DV was calculated as the difference between the highest and the lowest PEFR as a percentage of the mean PEFR on each day. For the whole group the median was 5.9%. DV was higher among smokers and among workers with work related pulmonary symptoms. Analysis of variance showed that only age (p = 0.012) and smoking (p = 0.016) had a significant effect on DV. Pulmonary symptoms, total IgE, and duration of occupation had no independent impact on DV, whereas the exposure level of grain dust tended (p = 0.082) to have an independent effect. Twelve workers had an abnormally high DV (greater than 20%), of whom seven showed no signs of obstructive respiratory disease by spirometry. If only a single spirometric test had been performed the tentative diagnosis of bronchial asthma could have been missed in these seven workers.     

Ventilatory function of factory workers exposed to tea dust

A cross-sectional study was conducted in order to determinethe prevalence of respiratory symptoms and the effect on ventilatorycapacity in workers exposed to tea dust for at least five yearsduring the sifting process of tea manufacture compared to acontrol group of field workers who were not exposed to tea dustpreviously. Fifty-three subjects each in the study and controlgroups were matched for age, sex, ethnic group and height. Prevalenceof chronic respiratory symptoms was obtained by questionnaire.Spirometric measurements included forced vital capacity (FVC),forced expiratory volume in the first second (FEV_1.0) and forcedmid-expiratory flow rate (FEF_25–75%). The study grouphad a chest radiograph. The odds ratio for any chronic respiratorysymptom was 11.6 (95% confidence interval [Cl] = 3.7–39.4)in the study group. Mean values for the spirometric tests werelower in the study group; the differences in FEV_1.0 and FEF_25–75%were significant. Tuberculosis was not found in the study group,while one subject (2.4%) had radiological evidence of bronchiectasis.It may therefore be concluded that chronic tea dust exposurecauses increased prevalence of respiratory symptoms and a significantdegree of small airways obstruction.     

Immunological findings in hemp workers.

Immunological status and its relation to respiratory findings were studied in 42 female textile workers occupationally exposed to hemp dust and in 49 female control workers. Skin prick tests with hemp or flax dust extracts from different parts of the mill in hemp workers demonstrated the following frequencies of positive tests to antigens: a mixture of hemp and flax extracts (64%), followed by flax extracts (48%), hemp from combing machines (41%), hemp from carding machines (38%), hemp from spinning and weaving machines (33%), and hemp from softening machines (20%). The prevalence of positive skin tests to hemp or flax allergens in control workers was consistently lower, ranging from 21 to 5%. Increased total serum IgE was recorded in 35.7% of hemp workers compared to only 5.0% of control workers (P < 0.05). Hemp workers with positive skin tests had significantly higher prevalences of chronic respiratory symptoms than those with negative skin tests. There were, however, no differences for acute symptoms between workers with positive and negative skin tests. Across-shift changes and baseline lung function were not different when compared by immunologic status. We showed additionally that a water-soluble extract of hemp dust causes a dose-related contraction of nonsensitized guinea pig tracheal smooth muscle when studied in vitro. Our results suggest that frequent immunologic abnormalities can be documented in hemp workers but, with the exception of chronic respiratory symptoms, in general, these do not correlate with respiratory findings.     

Occupational asthma caused by samba (Triplochiton scleroxylon) wood dust in a professional maker of wooden models of airplanes: A case study

Objectives

Wood dust is a known occupational allergen that may induce, in exposed workers, respiratory diseases including asthma and allergic rhinitis. Samba (obeche, Triplochiton scleroxylon) is a tropical tree, which grows in West Africa, therefore, Polish workers are rarely exposed to it. This paper describes a case of occupational asthma caused by samba wood dust.

Material and Methods

The patient with suspicion of occupational asthma due to wood dust was examined at the Department of Occupational Diseases and Clinical Toxicology in the Nofer Institute of Occupational Medicine. Clinical evaluation included: analysis of occupational history, skin prick tests (SPT) to common and occupational allergens, determination of serum specific IgE to occupational allergens, serial spirometry measurements, metacholine challenge test and specific inhalation challenge test with samba dust

Results

SPT and specific serum IgE assessment revealed sensitization to common and occupational allergens including samba. Spirometry measurements showed mild obstruction. Metacholine challenge test revealed a high level of bronchial hyperactivity. Specific inhalation challenge test was positive and cellular changes in nasal lavage and induced sputum confirmed allergic reaction to samba.

Conclusions

IgE mediated allergy to samba wood dust was confirmed. This case report presents the first documented occupational asthma and rhinitis due to samba wood dust in wooden airplanes model maker in Poland.     

Chronic and acute respiratory effects among grain mill workers

Exposure to flour dust may induce chronic respiratory manifestations as well as acute ventilatory effects. We compared the prevalence of respiratory symptoms, ventilatory impairment, and variations in pulmonary function over the workshift in a group of mill workers exposed to wheat flour and in referent workers. One hundred and forty-two men exposed to flour in a mill and 37 referent workers were included in this study. Each subject completed a standardized questionnaire. Pulmonary function tests were performed before and after the workshift. The assessment of environmental exposure to flour showed high concentrations during some jobs with a high percentage of inhalable particles and a low concentration of respirable particles. The exposed workers had a significantly higher prevalence of usual cough and usual phlegm than the referents. The prevalence of asthma, based on the questionnaire, was similar. Before the workshift, the exposed workers had significantly lower mean lung function values for peak flow rate and forced expiratory flow rate at 75% of the vital capacity than the referents. After the workshift, all the lung function values showed a slight decrease, significant for forced vital capacity and forced expiratory volume during 1 s in both groups. Among the exposed workers, the asthmatic subjects had a significantly higher decrease across the shift than the nonasthmatic workers. This result is probably linked to bronchial hyperreactivity. Among nonasthmatic subjects, the decrease was larger in nonexposed workers than in exposed workers. A higher prevalence of respiratory symptoms and lower pulmonary function values were observed among mill workers by comparison with referents. Moreover, the data suggest that asthmatic status and the time of spirometric measurements need to be taken into account in epidemiological studies on exposure to airborne allergens. In addition, the study does not exclude a healthy worker effect with selection of dust-resistant subjects or better identification of asthmatic subjects among the workers exposed to an allergenic substance than among the nonexposed workers.