Three patients with probable aerotoxic syndrome.

Introduction: "Aerotoxic syndrome" is a debated entity. Regulatory authorities consider long-term health effects to be an unlikely consequence of exposure to contaminated air because several air quality monitoring studies report low concentrations of toxic chemicals in cabin air. We describe two pilots and one flight attendant, who developed ill health during their flying career which improved after cessation of flying.Case details: The most frequently reported symptoms were headache, balance problems, fatigue, gastro-intestinal complaints and cognitive impairment. One of these patients had reduced levels of butyrylcholinesterase after a flight suggesting exposure to organophosphate compounds had occurred. All three were found to have elevated neuronal and glial auto-antibodies, biomarkers of central nervous system injury, and all three had genetic polymorphisms of paraoxonase (PON-1) and two of cytochrome P450, leading to a reduced ability to metabolize organophosphate compound (OPs).Discussion: A similar constellation of symptoms has been described in other studies of aircrew, although objective evidence of exposure is lacking in most of these studies. Reduced levels of butyrylcholinesterases in one of our cases is suggestive of causation and elevated neuronal and glial autoantibodies provide objective evidence of damage to the central nervous system. We consider further research is warranted.

Work-related upper extremity disorders: one-year follow-up in an occupational diseases registry.

PURPOSE: To study the course and consequences of work-related upper extremity disorders in the registry of the Netherlands Centre for Occupational Diseases (NCvB). METHODS: A follow-up study was performed in a sample of consecutive cases of work-related upper extremity disorders notified to the NCvB. Perceived severity was measured with VAS (0-100), quality of life with VAS (0-100) and SF-36, functional impairment with DASH and sickness absence with a questionnaire. Measurements took place directly after notification (T0) and after 3, 6 and 12 months (T1-T3). A linear mixed model was used to compare scores over time. RESULTS: Average age of the 48 consecutive patients (89% response) was 42 years; 48% were men. Perceived severity, functional impairment and sickness absence decreased statistically significant during the follow-up period, and quality of life scores improved. Patients older than 45 years scored worse on perceived severity of the disease, functional impairment and quality of life than did younger patients. CONCLUSIONS: The role of registries of occupational diseases for preventive policy can be extended by creating longitudinal data in sample projects. In the sample from our registry, work-related upper extremity disorders had a favourable course.

Notification of occupational skin diseases by dermatologists in The Netherlands.

BACKGROUND: A voluntary surveillance scheme of occupational skin diseases (OSDs) in The Netherlands starting in 2001 aimed to improve insight in the incidence of OSD especially occupational contact dermatitis (OCD), risk professions and causal agents. This paper presents the results of this scheme during 2001-05. METHODS: Reports of new cases of OSD received from the participating dermatologists on a monthly basis were analysed. Data evaluated included information on diagnosis, sex, age, sickness, absenteeism, profession and causal agents. Relative differences in incidence rates between industries or branches were estimated by calculating incidence rate ratios. RESULTS: About 80% of the notifications concerned OCD. The highest number of notifications was recorded in the first year of the scheme. This was probably due to reporting of a mixture of incident and prevalent cases. During the following 5 years, the number of yearly notifications of OSD declined. Hairdressers, nurses, metalworkers, mechanics and cleaners were the most commonly affected professions. Wet work and irritating substances were the most frequently reported causal agents. Most patients with OCD were not absent from work. CONCLUSIONS: A voluntary surveillance scheme with dermatologists provides valuable data about the distribution of OCD in risk professions and the causal agents. However, it has certain limitations in assessing trends in incidence. Active medical surveillance in populations at risk should be encouraged not only to improve secondary prevention but also to obtain more reliable information about the incidence of OCD.

Prevention of work-related airway allergies; summary of the advice from the Health Council of the Netherlands.

The Health Council of the Netherlands published a report in which the best procedure and method for recommending health-based occupational exposure limits (OELs) for inhaled allergens were identified by evaluating the scientific state of the art. Many respiratory disorders in the workplace arise from inhalation of substances which can cause allergy. To protect workers against respiratory allergy, various preventive measures are taken, one of them being reduction of exposure by setting legally binding standards. These are based on health-based OELs that specify a level of exposure to an airborne substance, a threshold level, below which it may reasonably be expected that there is no risk of adverse health effects. The Council is of the opinion that an OEL should prevent against allergic sensitization, as sensitization plays a crucial biological role and is a prerequisite for the development of allergy. Furthermore, the Council considers it most likely that the exposure level below which no allergic sensitization develops for most allergens is so low, that OELs are difficult to set with the current knowledge and technical feasibilities. An alternative approach is to accept exposure, which carries a small predefined risk in developing allergic sensitization. In addition, it is worth considering periodic screening of exposed workers on allergic sensitization, because timely intervention can prevent worse. The feasibility of periodic screening and what else is needed to comply with the most important criteria, should however be judged case-by-case.

Sentinel surveillance of occupational diseases: a quality improvement project.

BACKGROUND: Occupational diseases are generally underreported. The aim of this study was to evaluate whether a sentinel surveillance project comprising motivated and guided occupational physicians would provide higher quality information than a national registry for a policy to prevent occupational diseases. METHODS: A group of 45 occupational physicians participated in a sentinel surveillance project for two years. All other occupational physicians (N = 1,729) in the national registry were the reference group. We compared the number of notifications per occupational physician, the proportion of incorrect notifications, and the overall reported incidence of occupational diseases. RESULTS: The median number of notifications per occupational physician during the project was 13.0 (IQR, 4.5-31.5) in the sentinel group versus 1.0 (IQR, 0.0-5.0) in the reference group (P < 0.001). The proportion of incorrect notifications was 3.3% in the sentinel group and 8.9% in the reference group (P < 0.001). The overall reported occupational disease incidence was 7 times higher (RR = 6.9, 95% CI: 6.5-7.4) in the sentinel group (466 notifications per 100,000 employee years) than in the reference group (67 notifications per 100,000 employee years). CONCLUSIONS: A sentinel surveillance group comprising motivated and guided occupational physicians reported a substantially higher occupational disease incidence and a lower proportion of incorrect notifications than a national registry.

Employment and disability for work in patients with COPD: a cross-sectional study among Dutch patients.

OBJECTIVES: The aim was to gain insight into work experiences and problems of subjects with chronic obstructive pulmonary disease (COPD) to develop more effective guidelines for preventing work disability and work loss. METHODS: A total of 617 patients aged 45-60, recruited from pulmonary outpatient clinics and general practices, completed a questionnaire on (respiratory) health and work history. RESULTS: Of the patients 43% were female, 52% were employed and more than half were less educated. Comorbidity was present in 52% of the study group. Of those who stopped working (N=260), 36% stopped before the onset of COPD, 39% stopped because of COPD and 25%, although having COPD, had other reasons to stop. Of the patients with a work history 39% had an invalidity benefit: 21% of the working and 60% of the non-working patients. For one-third of these patients COPD was not the reason for having an invalidity benefit. For 56% of those who had a benefit because of COPD, comorbidity contributed to work disability. No difference in current smoking habit was seen between working patients and non-working patients. Yet, non-working patients were more often smokers at the moment they stopped working. Furthermore, former smokers who still worked stopped smoking at a younger age than former smokers who stopped working. Compared with workers and independent of smoking habit, former workers were more exposed to dust/irritants, had their work(place) less frequently modified and had more unfavourable (social) work experiences. CONCLUSION: For employees with COPD, work loss is often multi-factorial. Comorbidity is often present and an important cause for work loss. Therefore occupational health guidance has to take other interfering (health) factors than COPD into consideration as well. In preventing work disability, work(place) adjustment merits more attention.

Factors affecting FEV1 in workers with potroom asthma after their removal from exposure.

OBJECTIVE: In this study the relationship has been studied between exposure time and potential prognostic factors and FEV1 percent predicted (FEV1-% pred) in workers with potroom asthma, after their transfer from exposure to exposure-free departments. METHODS: Between 1970 and 1990 in a Dutch aluminium-production plant, 179 workers had been diagnosed as having potroom asthma. We carried out a follow-up study (n = 122) in the population still present at the factory 5 years after their relocation to an exposure-free department. In this study population, we examined the relationship between FEV1-% pred at follow-up, and exposure time: the time interval between start of exposure and diagnosis. To correct for confounding factors, we included age, pre-employment FEV1-% pred, allergy, medical treatment, and smoking in the analysis. RESULTS: The mean FEV1-% pred at follow-up was within the normal range (90.3, SD 13.5). Long exposure time was significantly associated with a low FEV1-% pred at follow-up (P = 0.0046). Adjustment was necessary for pre-employment FEV1-% pred and current smoking as confounding factors. CONCLUSION: Long duration of exposure is a factor affecting FEV1 in workers with potroom asthma. The results of this study give support for additional preventive measures to be taken, such as early recognition of work-related respiratory complaints and repeated education.

Exposure and acute exposure-effects before and after modification of a contaminated humidification system in a synthetic-fibre plant.

OBJECTIVE: Follow-up study of exposure and acute exposure-effects after modification to steam humidification of a contaminated cold water system which had caused an outbreak of humidifier fever in a synthetic-fibre plant. METHODS: Before and after modification of the system aerobiological measurements were performed. Concentrations of fungi and bacteria, in colony forming units (cfu) per m3, were measured by stationary air sampling with an Andersen sampler. Endotoxin levels (pg/m3) were determined by Limulus Amoebocyte Lysate (LAL) assay in pooled dust from personal air sampling. An indication of exposure levels of oil-mist was obtained by monitoring with a direct reading optical photometer. Changes as acute exposure-effects in spirometry and white blood cell count, during an afternoon shift were compared in exposed and non-exposed workers before and after modification. RESULTS: Measured levels of fungi, total bacteria, Gram-negative bacteria and endotoxins both before and after modification were below levels which would be expected to be associated with the exposure-effects. However, after modification, we found that the statistically significant differences in levels of bacteria and endotoxins with a department without humidification no longer existed. Mean oil-mist concentrations were below 1 mg/m3, with short-time peak exposure during certain tasks of up to 5 mg/m3. Before modification, in exposed workers there was significantly more decline of spirometry, and more increase of white blood cell count during the first afternoon shift, compared with non-exposed workers. In exposed workers, the white blood cell count increase was positively associated with decline of spirometry. After modification, differences between exposed and non-exposed workers no longer existed. CONCLUSION: Follow-up investigation of acute exposure-effects demonstrated the effectiveness of remedial actions taken against a contaminated humidification system. Follow-up of exposure-effects in particular is recommended when there is doubt about the interpretation of exposure measurements.

Follow-up study of workers in a nylon carpet yarn plant after remedial actions taken against a contaminated humidification system.

OBJECTIVE: To investigate the effectiveness of remedial actions taken against a contaminated humidification system, after an outbreak of humidifier disease in a nylon carpet yarn plant. METHODS: Two and 6 years after modification, a follow-up investigation of a stratified (age, smoking habits) sample of exposed (n = 75) and non-exposed (n = 56) workers was carried out. Outcome-parameters were: respiratory symptoms, spirometry, skin tests and serology with various humidifier fungi. In addition, the yearly incidence of work-disability because of chronic respiratory disease during the 2 years before, and 11 years after the modification was compared. RESULTS: At follow-up, exposed workers, who remained at the same workplace no longer had significantly more frequent chronic respiratory symptoms. The prevalence of positive serology was still higher (P < 0.05) in exposed workers after 2 years, but at the 6 year follow-up investigation, the difference was no longer significant. Prevalence of positive skin tests after 2 years no longer differed from that of the non-exposed workers. Slopes (ml/years) of the graphs of forced vital capacity (FVC) and one-second forced expiratory volume (FEV1) during the 6 year follow-up after the first investigation did not differ between exposed and non-exposed workers, both before and after adjustment for age, smoking habits and results of skin tests and serology before modification. Before modification, exposed workers with a positive late skin test had a lower FVC than non-exposed workers. After 6 years of follow-up their FVC was still lower, but the difference was no longer significant. There were no indications of selective loss to follow-up. After remedial actions no new cases of humidifier disease occurred. Moreover, the yearly incidence of work-disability in this plant because of chronic respiratory disease, decreased from 1.30% to 0.27% compared with a decrease from 0.30% to 0. 12% in other synthetic fibre plants. CONCLUSION: Follow-up investigation of exposure-effects demonstrated the effectiveness of remedial actions taken against a contaminated humidification system.

Follow up investigation of workers in synthetic fibre plants with humidifier disease and work related asthma.

OBJECTIVE: To investigate the clinical and sociomedical outcome in patients with various clinical manifestations of humidifier disease and work related asthma after removal from further exposure. METHODS: Follow up investigation (range 1-13 years) of respiratory symptoms, spirometry, airway responsiveness, sickness absence, and working situation in patients with (I) humidifier fever (n = 12), (II) obstructive type of humidifier lung (n = 8), (III) restrictive type of humidifier lung (n = 4), and (IV) work related asthma (n = 22). All patients were working at departments in synthetic fibre plants with microbiological exposure from contaminated humidification systems or exposure to small particles (< 1 micron) of oil mist. RESULTS: At follow up patients with work related asthma were less often symptom free (37%, 7/19) than patients with humidifier disease (I, II, III) (67%, 16/24). Mean forced expiratory volume in one second (FEV1) of patients with obstructive impairment had been increased significantly at follow up but still remained below the predicted value. Mean forced vital capacity (FVC) of patients with initially restrictive impairment had returned to normal values at follow up. Airway hyperresponsiveness at diagnosis persisted in patients with obstructive impairment (II + IV 14/17, but disappeared in patients with humidifier fever (3/3) and restrictive type of humidifier lung (2/2). In patients with obstructive impairment (II + IV), FVC and FEV1 at diagnosis were negatively associated with the duration between onset of symptoms and diagnosis and the number of years of exposure. Those with positive pre-employment history of respiratory disease had a lower FEV1 at diagnosis. Sickness absence due to respiratory symptoms decreased in all groups of patients after removal from further exposure, but this was most impressive in patients with the humidifier lung (II, III) and patients with work related asthma (IV). At follow up 83% of the patients were still at work at the same production site, whereas 11% received a disability pension because of respiratory disease. CONCLUSION: In patients with work related respiratory disease caused by exposure from contaminated humidification systems or oil mist, removal from further exposure resulted in clinical improvement, although, especially in those with obstructive impairment, signs persisted. Because of the possibility of transferring patients to exposure-free departments most patients could be kept at work.

Occurrence of occupational asthma in aluminum potroom workers in relation to preventive measures.

The purpose of this study was to investigate whether preventive measures such as reduction of exposure and the introduction of the histamine provocation test (HPT) as a selection instrument resulted in a lower incidence of potroom asthma (PA) and a longer time lag between the commencement of employment and the occurrence of PA. Between 1970 and 1990, 179 cases of PA were diagnosed. This period was divided into three periods. During period 1 (1970-1975), no exposure data were available. Period 2 (1976-1981) is characterized by known exposure data obtained by means of fluoride determinations in urine. At the beginning of period 3 (1982-1990) the HPT was incorporated into the preemployment medical examination. We computed the incidence density (ID) in the three periods and analyzed the timelag in relation to the year of employment and confounding factors such as age, atopic history, blood eosinophil counts, lung function, smoking habits at preemployment, and exposure level. After introduction of the preemployment HPT the ID decreased, but cases continued to occur (ID 11.6 in period 2 versus 2.5 in period 3). The time lag was did not differ when subjects with bronchial hyperresponsiveness were screened out. The exposure level and an atopic history were factors associated with the period of employment and, therefore, confounded the results. The results of this study support the role of an atopic history as a risk factor for development of PA at lower exposure levels and suggest that potroom exposure not only incites asthmatic symptoms but also acts as an inducer of respiratory disease.

The clinical spectrum of humidifier disease in synthetic fiber plants.

In a synthetic fiber production site with recirculating cold water humidification systems and small-size-particle (> 0.1 mu < 1 mu) oil mist exposure, humidifier disease was diagnosed in several workers. The patients could be divided into three groups illustrating the clinical spectrum of humidifier disease: humidifier fever (toxic inhalation fever) (12 patients): an asthma-like syndrome (8 patients); and allergic alveolitis (4 patients). Natural challenge at the work place, monitored by parameters such as peak-flow, spirometry, blood leucocyte count, and body temperature, provided important diagnostic information. In patients with chronic allergic alveolitis, a gradual recovery during an exposure-free period indicated a work-related causation, more than changes during challenge in normal work. In some patients, the fungus Sporothrix schenckii, hitherto unknown as a sensitizer, may have been at least one of the causative antigens. Measured levels of viable fungi (< or = 100 CFU/m3) and endotoxin (64 pg/m3) in air samples were much lower than those at which health effects usually are reported. Small-size-particle oil mist exposure may have underestimated the exposure to microorganisms, but otherwise an adjuvant role to this type of co-exposure might also be postulated. In contrast to allergic alveolitis, the asthma-like syndrome appeared to be more common in patients with a history of atopy and of smoking.

Occupational asthma in aluminium potroom workers related to pre-employment eosinophil count.

Occupational asthma still occurs in aluminium potroom workers despite pre-employment medical selection. The purpose of our study was to identify workers with an increased risk of developing "potroom asthma". A nested, case-control study was carried out in two Dutch aluminium producing plants. Pre-employment data of 364 potroom workers (182 cases and 182 controls) were analyzed. Cases were workers unable to work because of work-related respiratory disease, meeting the criteria for potroom asthma. The selected controls were matched for age, year of starting employment and working conditions. Pre-employment eosinophil count was significantly related to the occurrence of potroom asthma, even though the mean number of the eosinophils in cases was within the normal range (< 275 cells.mm-3; 0.28 cells x 10(9).L-1). Hence, 39 of the 45 individuals with blood eosinophil counts in the upper range of normal (> 220 cells.mm-3; 0.22 cells x 10(9).L-1) developed potroom asthma with time. We conclude that workers without respiratory symptoms, with normal lung function and normal bronchial responsiveness before employment developed potroom asthma. Fluoride exposure, combined with an elevated eosinophil count, might induce an immunological or cytotoxic process.

Use and safety of a shortened histamine challenge test in an occupational study.

A shortened histamine challenge test was used in a study of occupational airway disease. We evaluated the safety, defined as the absence of a decrease in forced expiratory volume in one second (FEV1) of greater than 40%. The occurrence of complaints, the repeatability of test results, and the average amount of time saved were measured. A standard protocol was used comprising 30 s tidal breathing with sequential doubling concentrations from 1 to 32 mg.ml-1 histamine. Subjects with no indication of hyperresponsive airways started at 4 mg.ml-1. If the decrease in FEV1 was < 6%, a concentration step was skipped (fourfold increase in concentration). The test was terminated when the decrease in FEV1 was at least 18%. A total of 697 subjects performed a test. All subjects with a provocative concentration of histamine producing a 20% decrease in FEV1 (PC20) value of < or = 4 mg.ml-1 (n = 16) started at the lowest concentration. Six subjects reached a > or = 20% decrease in FEV1 (range 21-24%) after a fourfold increase in concentration. Five subjects had a decrease in FEV1 of greater than 40%, and this decrease occurred after a doubling concentration. Cough, flushing, and chest tightness were noted in 18% of the subjects. In 56% of the tested subjects, the shortest provocation scheme (phosphate solution followed by 4, 16 and 32 mg.ml-1 histamine) was applied, resulting in a time reduction of nearly 50% per test, and reducing the time needed to complete the study from 5 to 3 months. The shortened test was repeatable within one concentration difference.(ABSTRACT TRUNCATED AT 250 WORDS)

Airway hyperresponsiveness in workers exposed to low levels of irritants.

The purpose of this study was to assess the association between occupational exposure to low levels of airway irritants, and airway responsiveness to histamine. In 688 male workers, symptom prevalence was assessed according to the British Medical Research Council (BMRC) questionnaire. All subjects performed a 30 s tidal breathing challenge test. Airway hyperresponsiveness (AHR) was defined as a 20% fall in forced expiratory volume in one second (FEV1) at < or = 32 mg.ml-1 histamine. On the basis of job titles and working department, the exposure status of all workers was characterized into seven groups: 1) reference group; 2) white collars; 3) SO2, HCl, SO4(2-); 4) polyester vapour; 5) oil mist and oil vapour; 6) polyamide and polyester vapour; and 7) multiple exposures. Using multiple logistic regression, no association was found between the exposure groups and a higher prevalence of AHR. A higher prevalence was significantly associated with a low FEV1, a history of allergy, and the presence of chronic respiratory symptoms. Subjects in the SO2 group and the oil mist group with < or = 5 exposure years had a lower prevalence of AHR, probably due to pre-employment selection procedures. There was some trend for subjects with more than 5 yrs exposure to polyester vapour and to oil mist and to oil vapour to have a higher prevalence of AHR. Analyses using the dose-response slope according to O'Connor, revealed similar results and provides no additional information. We conclude that no association could be demonstrated between low grade exposure to airway irritants and airway hyperresponsiveness, and that further research is needed to elucidate this relationship.

Airway hyper-responsiveness and the prevalence of work-related symptoms in workers exposed to irritants.

The association between exposure to airway irritants and the presence of work-related symptoms and whether this association was modified by airway hyper-responsiveness, smoking, and allergy by history was studied in 668 workers of synthetic fiber plants. A Dutch version of the British Medical Research Council (BMRC) questionnaire with additional questions on allergy and work-related symptoms was used to assess symptoms, and a standardized histamine challenge test of airway hyper-responsiveness (AHR) was employed. Work-related symptoms were defined as having more than usual eye and respiratory symptoms during work. On the basis of job titles and working department, the exposure status of all workers was characterized into seven groups: (1) reference group; (2) white collars; (3) SO2, HCl, SO4(2-); (4) polyester vapor; (5) oil mist and oil vapor; (6) polyamide and polyester vapor; and (7) multiple exposure. The association between exposure groups and work-related symptom prevalence was estimated by means of multiple logistic regression. The overall prevalence of the work-related symptoms were: cough 9%; phlegm 6%; dyspnea 7%; wheeze 2%; eye symptoms 16%; nasal symptoms 15%. Exposure to airway irritants was significantly associated with work-related symptoms, independent of AHR, smoking, allergy by history, and chronic respiratory symptoms. The association of exposure group with work-related symptoms was stronger for subjects with AHR than for subjects with no AHR. The association with dyspnea and/or wheeze was also stronger for smokers than for nonsmokers and ex-smokers. In contrast, the association between exposure and a higher prevalence of work-related symptoms was stronger in subjects with no history of allergy than in subjects with history of allergy. This is most likely due to the relatively high prevalence of background symptoms in (nonexposed) allergic subjects. It is concluded that exposure to irritants in the working environment might lead to respiratory symptoms, even if exposure levels are relatively low.

Airway hyperresponsiveness, prevalence of chronic respiratory symptoms, and lung function in workers exposed to irritants.

The association between occupational exposure to airway irritants and the prevalence of chronic respiratory symptoms and level of lung function, and whether these associations were modified by airway hyperresponsiveness, smoking, and a history of allergy were studied in 668 workers from synthetic fibre plants. Respiratory symptoms were recorded with a self administered Dutch version of the British Medical Research Council questionnaire, with additional questions on allergy. Airway responsiveness was measured by a 30 second tidal breathing histamine challenge test. On the basis of job titles and working department, the current state of exposure of all workers was characterised as (1) no exposure, reference group; (2) white collar workers; (3) SO2 HCl, SO4(2); (4) polyester vapour; (5) oil mist and vapour; (6) polyamide and polyester vapour; (7) multiple exposure. Workers exposed to airway irritants were not simultaneously exposed to airborne dust. Airway hyperresponsiveness (AHR), defined as a 20% fall in forced expiratory volume in one second (FEV1) at < or = 32 mg/ml histamine, was present in 23% of the subjects. The association between exposure groups and prevalence of symptoms was estimated by means of multiple logistic regression; the association with level of lung function (forced vital capacity (FVC), FEV1, maximum mid-expiratory flow rate (MMEF)) was estimated by means of multiple linear regression. Both methods allow simultaneous adjustment for potential confounding factors. The exposure groups were associated with a higher prevalence of chronic respiratory symptoms. Lower prevalence of symptoms was found for workers exposed to SO2, HCl, and SO4(2-), most likely due to pre-employment selection procedures. Current smoking, AHR, and a history of allergy were significantly associated with a higher prevalence of chronic respiratory symptoms, independent of each other, and independent of irritant exposure. The association between exposure and prevalence of symptoms was greater in smokers than in ex-smokers and non-smokers. This difference was most clearly seen in the polyester vapour and polyamide and polyester vapour group. No modification of the association between exposure groups and prevalence of symptoms by airway hyperresponsiveness could be shown. The exposure groups were not significantly associated with a lower level of lung function. Adjustment for chronic respiratory symptoms did not change the results. There were no indications of a possible interaction between exposure and AHR, current smoking, or a history of allergy on lung function. Workers of the polyester vapour and the oil mist and vapour group with >10 years of exposure had a lower FEV1 (beta = -295 and -358 ml) and significantly lower MMEF (beta = -1080 and -1247 ml/s; p < 0.05) than the reference group. The number of workers of both group were, however, small (n = 10 and n = 13 respectively). More investigations between low level exposure to irritant and respiratory health.