Respiratory symptoms, lung function, and nasal cellularity in Indonesian wood workers: a dose-response analysis

Effects of mixed hardwoods dust on respiratory function and blood immunoglobulin levels in wood workers

Background

Occupational exposure to wood dust, generated by various individual wood species, both softwood and hardwood, has been extensively documented as a causative factor for reduced lung function, frequent respiratory symptoms, and increased immunological responses in wood workers. This study explores the impact of wood dust from mixed tropical hardwood species on lung function, respiratory symptoms, and Immunoglobulin (Ig) E and G levels.

Methods

A cross-sectional study was conducted among wood workers at the Accra Timber Market and a control group from the University of Ghana. Particulate matter (PM) was sampled using a Minivol Sampler set to a flow rate of 5 l/min. Respiratory symptoms were assessed using questions adapted from the British Medical Research Council (MRC) questionnaire (1960). Lung volumes and airflow rates were measured using a spirometer. Total serum IgE and IgG levels were quantified using ELISA.

Results

No significant differences were observed between the wood workers and the controls for demographic variables. Wood workers exhibited a significantly higher prevalence of respiratory symptoms, particularly rhinitis, with many reporting the absence of symptoms during holidays. Lung function parameters (VC, FEV1, FEV1%, PEFR, and FEF25-75%) were significantly reduced (p < 0.05) in wood workers. A significant negative correlation was noted between lung function parameters and years of exposure to wood dust. Wood workers showed significantly elevated levels (p < 0.05) of IgG and IgE.

Conclusion

The study findings suggest that exposure to mixed tropical hardwood dust induces elevated blood IgE and IgG levels, along with non-allergic respiratory function abnormalities.

Dynamics of pre-shift and post-shift lung function parameters among wood workers in Ghana

Background

Diseases affecting the lungs and airways contribute significantly to the global burden of disease. The problem in low- and middle-income countries appears to be exacerbated by a shift in global manufacturing base to these countries and inadequate enforcement of environmental and safety standards. In Ghana, the potential adverse effects on respiratory function associated with occupational wood dust exposure have not been thoroughly investigated.

Methods

Sixty-four male sawmill workers and 64 non-woodworkers participated in this study. The concentration of wood dust exposure, prevalence and likelihood of association of respiratory symptoms with wood dust exposure and changes in pulmonary function test (PFT) parameters in association with wood dust exposure were determined from dust concentration measurements, symptoms questionnaire and lung function test parameters.

Results

Sawmill workers were exposed to inhalable dust concentration of 3.09 ± 0.04 mg/m3 but did not use respirators and engaged in personal grooming habits that are known to increase dust inhalation. The sawmill operators also showed higher prevalence and likelihoods of association with respiratory symptoms, a significant cross-shift decline in some PFT parameters and a shift towards a restrictive pattern of lung dysfunction by end of daily shift. The before-shift PFT parameters of woodworkers were comparable to those of non-woodworkers, indicating a lack of chronic effects of wood dust exposure.

Conclusions

Wood dust exposure at the study site was associated with acute respiratory symptoms and acute changes in some PFT parameters. This calls for institution and enforcement of workplace and environmental safety policies to minimise exposure at sawmill operating sites, and ultimately, decrease the burden of respiratory diseases.

The association between wood dust exposure and respiratory disorders and oxidative stress among furniture workers

BACKGROUND

This study was undertaken to determine the effect of wood dust on the respiratory system and oxidative stress in furniture workers and to determine whether any associations exist between respiratory parameters and oxidative stress.

METHODS

This cross-sectional study was performed on 45 furniture workers and 45 office workers as a reference group in Iran. The NIOSH method 0600 was used to determine the concentration of particulates. The prevalence of respiratory symptoms was estimated via the European Community Respiratory Health Survey (ECRHS) questionnaire. Oxidative stress biomarkers and respiratory parameters were also measured.

RESULTS

The mean concentrations of respirable and non-respirable dust were found to be 1.51 mg/m³ and 1.23 mg/m³, respectively. Pulmonary function parameters, including forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), FEV1/FVC, and antioxidant capacity biomarkers such as total antioxidant capacity (TAC) and superoxide dismutase (SOD) were significantly lower, while the prevalence of respiratory symptoms, and malondialdehyde (MDA) levels, were significantly higher in the furniture workers than in the reference group. There were significant positive associations between FVC and FEV1 with SOD and TAC.

CONCLUSION

The present study results indicated that exposure to wood dust significantly increased respiratory disorders and confirmed the association between lung function parameters and oxidative stress.

The impact of wood dust on pulmonary function and blood immunoglobulin E, erythrocyte sedimentation rate, and C‐ reactive protein: A cross‐sectional study among sawmill workers in Tangail, Bangladesh

Background and Aims

Occupational exposure to wood dust leads to lung function abnormalities that are prominent causes of morbidity and disability of sawmill workers. The adverse respiratory effects of wood dust in sawmills have not been studied thoroughly in Bangladesh. This study aimed to investigate the effect of wood dust on the respiratory health of sawmill workers compared to controls as well as to determine the association of wood dust‐exposing effects with inflammatory blood biomarkers, such as immunoglobulin E (IgE), erythrocyte sedimentation rate (ESR), and C‐reactive protein (CRP).

Methods

This cross‐sectional study included 100 sawmill workers from 25 distinct sawmills in various areas of Tangail, Bangladesh as well as 100 healthy volunteers who were adopted as a control group. Questionaries' survey and pulmonary function tests were performed face to face. Furthermore, after performing lung function tests, blood was drawn for further IgE, ESR, and CRP analyses.

Results

Respiratory symptoms including breathlessness (32%), coughing (39%), sneezing (43%), chest tightness (30%), and itching (40%) were significantly higher in sawmill workers compared with control. Besides, sawmill workers' exposure to wood dust revealed a significantly lower level of spirometry parameters (forced vital capacity ​​​​​[FVC], FVC (%), forced expiratory volume in 1 s [FEV1], FEV1 (%), peak expiratory flow [PEF], PEF (%), FEV1/FVC (%), FEF25, FEF75, and FEF2575) compared with control and these spirometry parameters decreased with the increasing length of service. Moreover, a significantly higher level of IgE was observed in sawmill workers (290.90 ± 39.49) than in the control (120.95 ± 23.00). The high level of IgE suggests that the lower pulmonary function may be linked to allergic responses to wood dust among sawmill workers.

Conclusion

This study suggested that exposure to wood dust can cause impairment of respiratory function along with high IgE levels.

Prevalence of respiratory symptoms and spirometric changes among non-smoker male wood workers

Objective

To assess the effects of workplace exposure to hardwood dust on lung function and determine a prevalence of respiratory symptoms among wood workers.

Study design

Cross-sectional observational study.

Setting

Tertiary referral center.

Subjects and methods

Two hundred seventy-six, non-smoker male wood workers and equal number of non-smoker male office workers, referred to pulmonology clinic included in this study. Evaluation of study participants included completion of a questionnaire regarding respiratory symptoms and baseline spirometry was measured according to the actual recommendations.

Results

Respiratory symptoms including cough, phlegm, chest tightness, and wheezing were significantly higher in wood workers than office workers (40.2% versus 29.3% for cough, p = 0.0073; 40.6% versus 23.6% for phlegm, p<0.0001; 38.0% versus 23.1% for chest tightness, p = 0.0001; 25.3% versus 14.5% for wheezing, p = 0.0014).

No statistically significant differences were observed for Dyspnea, and upper respiratory tract symptoms among wood workers compared to office workers. While wood workers were more likely to require spirometry test than office workers (21.4% versus 5.4%, p<0.001) the obstructive changes were more prevalent on spirometry test in wood workers (71.4% obstructive pattern versus 28.6% restrictive pattern). Spirometry test revealed the mean values of FEV₁ and FEV₁/FVC ratio were significantly lower in the wood workers, compared to their mean values in the control group.

Conclusion

Respiratory symptoms associated with work, are more prevalent among wood workers than office workers. Our data revealed that workplace exposure to hardwood dust may compromise respiratory function, indicating the importance and the need for optimizing preventive measures in workplace to protect the respiratory health among exposed workers. Obstructive changes on pulmonary function test is a dominant pathologic pattern in pulmonary function test among wood workers. Further investigation is required by current available tools such as nasal cytology to detect influence of wood dust exposure on the upper respiratory airway.

New-onset COPD and Decline in Lung Function Among Wood Dust-Exposed Workers: Re-analysis of a 6-year Follow-up Study

Objectives

There is a lack of longitudinal studies exploring the association between organic wood dust exposure and new-onset chronic obstructive pulmonary disease (COPD) and change in lung function. We have re-investigated these associations in a 6-year follow-up cohort of furniture workers exposed to wood dust using improved outcome measures and methods.

Methods

A large follow-up study of 1112 woodworkers (63%) from the Danish furniture industry and 235 controls (57%) was conducted between 1998 and 2004. Forced expiratory volume in the first second (FEV1), forced vital capacity (FVC), and the ratio (FEV1/FVC) standardized for age, height, and sex using the Global Lung Function Initiative 2012 equations were assessed at baseline and follow-up. Questionnaires on respiratory symptoms, wood dust exposure, and smoking habits were collected. Exposure was assessed as exposure level at baseline and as cumulative exposure in the follow-up period from quantitative task specific job exposure matrix available at both baseline and follow-up based on personal dust sampling using passive dust monitors. The association between exposure to wood dust and new-onset COPD was assessed with logistic regression, whereas the association between wood dust and the longitudinal change in z-score for lung function was assessed with linear regression.

Results

Similar associations were seen for different exposure metrics. An exposure-response relation was seen for new-onset COPD for female smokers with an odds ratio (OR) (95% confidence interval [CI]) of 8.47 (0.9-82.4) in the highest exposed group compared to controls, and a significant test for trend P = 0.049. No such association was seen among males for whom only smoking was strongly associated to new-onset COPD. For change in lung function, a significant exposure-response was seen for females, confirming previous findings, with increasing levels of wood dust exposure showing larger decline in lung function (β [95% CI]: -0.32 ΔzFEV1 (-0.56 to -0.08, P = 0.009) for third quartile exposure compared to controls, test for trend, P = 0.005, equivalent to an excess loss of 125 ml in the 6 years of follow-up). An opposite association was seen for men.

Conclusion

In conclusion, we found that female woodworkers have a dose-dependent increased OR of new-onset COPD and an excess decline in lung function suggesting that female woodworkers may be more susceptible to wood dust exposure than male woodworkers. Among male woodworkers, only smoking and asthma were significant predictors for new-onset COPD and excess decline in lung function. These results emphasize that reduction in both smoking and wood dust exposure should continuously be an effort to prevent adverse pulmonary health effects.

Effect of Exposure to 2.5 μm Indoor Particulate Matter on Adult Lung Function in Jakarta

Objectives

Lung function impairment due to exposure to indoor air pollution of particulate matter size 2.5 micrometers (PM_2.5) is not well documented in Jakarta.

Methods

To assess whether there is an association between indoor PM_2.5 concentration and lung function impairment among the adult population, a cross-sectional design was implemented. There were 109 adults selected aged between 20 years and 65 years from the Pulo Gadung industrial area, East Jakarta. Association and logistic regression analysis were implemented for statistical analysis of the data.

Results

The average exposure to indoor PM_2.5 was 308 μg/m³. There were 38.5% of participants that had lung function impairment. PM_2.5 concentration was found to be associated with lung function impairment among the adult population living in Pulo Gadung industrial area after controlling for gender, duration of exposure, ventilation, smoking status, and humidity.

Conclusion

The results of this study suggest that PM_2.5 concentrations in the Pulo Gadung industrial area may be the main contributor to the impairment of lung function for adults living in the surrounding residential area.

Functional disorders of the lung and symptoms of respiratory disease associated with occupational inhalation exposure to wood dust in Iran

OBJECTIVES

The possible adverse respiratory effects of airborne pollutants in sawmills have not been thoroughly investigated in Iran. Additionally, the extent to which workers are exposed to this organic dust and its associated bioaerosols has not been extensively quantified. Likewise, the predominant bacterial and fungal species associated with wood dust have not been characterized. The present study was undertaken to address these issues.

METHODS

One hundred male individuals exposed to wood dust and 100 unexposed male subjects were investigated. They completed a standardized respiratory symptom questionnaire and underwent spirometry testing. Additionally, airborne concentrations of respirable and inhalable dust particles, bacteria, and fungi were measured.

RESULTS

The mean concentrations of inhalable and respirable dust particles, bacteria, and fungi were found to be 2.44, 6.76 mg/m³ , 756.38, and 299.15 colony-forming units/m³ , respectively. The predominant Gram-negative bacteria in the sawmills included the Pseudomonadaceae, Klebsiella pneumoniae, and Rhinoscleromatis spp., and the predominant fungi consisted of the zygomycetes and Aspergillus spp. Respiratory symptoms were significantly more prevalent among exposed workers. Significant cross-shift decrements were noted in some pulmonary function parameters. Similarly, pre-shift spirometry results indicated that some pulmonary function parameters were significantly lower in the exposed group.

CONCLUSIONS

Exposure to wood dust and its bioaerosols was associated with significantly higher prevalence of respiratory symptoms and both acute (i.e., partially reversible) and chronic (i.e., irreversible) decrements in the functional capacity of the lung. Additionally, the characterized bioaerosols did not differ significantly from those isolated in other parts of the world.

Early detection of lung cancer potential among Egyptian wood workers

Wood dust is known to be a human carcinogen, with a considerable risk of lung cancer. The increased cancer risk is likely induced through its genotoxic effects resulting from oxidative DNA damage. This study aimed at assessing the genotoxicity of wood dust and demonstrating the role of sputum PCR as a screening tool for early prediction of lung cancer among wood workers. The study was carried out in the carpentry section of a modernized factory involved with the manufacture of wooden furniture in Greater Cairo, Egypt. Environmental assessment of respirable wood dust concentrations was done. Frequency of chromosomal aberrations (CA%) and sister chromatid exchanges (SCE%) in peripheral blood lymphocytes (PBL) was assessed and comet assays were performed in samples from among the study population (n = 86). Levels of superoxide dismutase (SOD) and glutathione peroxidase (GPx) enzymes were measured. The polymerase chain reaction (PCR) was used to study hypermethylation of p16 and ̸or O6-methylguanine-DNA methyltransferase (MGMT) gene promoters in sputum DNA. The concentrations of respirable wood dust exceeded the Egyptian and international permissible limits with highest levels generated by sawing operations. Laboratory investigations revealed statistically significantly higher frequencies of CA and SCE as well as increased comet tail length associated with significant decrement in the levels of SOD and GPx among exposed group. A statistically significant elevation in the extent of hypermethylation was detected for the p16 and MGMT gene promoters in the sputum DNA of studied wood workers. The study results support the conclusion that prolonged unprotected occupational exposure to wood dust is associated with possible genotoxicity and oxidative stress that might raise the risk for carcinogenesis including lung cancer.

Self-employment in joinery: an occupational risk facor?

OBJECTIVES

Only a few studies have analyzed the health of self-employed workers. This cross-sectional study is the first to compare health status among craftsmen joiners and paid joiners.

MATERIAL AND METHODS

Clinical and paraclinical data for self-employed craftsmen and employees were collected by occupational health doctors according to a standardized protocol and compared. Health data and professional status relationships were analyzed by logistic regression.

RESULTS

A total of 171 craftsmen and 196 paid workers were included. Craftsmen had more dermatologic pathologies (odds ratio (OR) = 2.67, p < 0.05), ear/nose/throat symptoms (OR = 3.38, p < 0.001), pulmonary symptoms (OR = 2.46, p < 0.05), musculoskeletal symptoms (OR = 3.09, p < 0.001), and abnormal audiogram (OR = 3.50, p < 0.001). The FEV1 was significantly lower among craftsmen (p < 0.01), independently of tobacco smoke exposure.

CONCLUSIONS

This survey high-lights a high morbidity rate among self-employed craftsmen, suggesting that among woodworkers, professional status can be a risk factor for health. The preventive medical system for craftsmen has to be rethought to guarantee better safety for this population.

Validity of the COPD assessment test translated into local languages for Asian patients

OBJECTIVE

Our objective was to evaluate the validity of the COPD Assessment Test (CAT), translated locally, for measuring the health status of patients in Asian countries.

METHODS

A pooled analysis of cross-sectional studies from Indonesia, Korea, Vietnam, and Hong Kong was performed. Smokers or ex-smokers, aged ≥ 40 years, with a smoking history of ≥ 10 pack-years and a COPD diagnosis in the past 6 months or more were recruited. Demographic, smoking, and COPD history and spirometry data were collected from patients who completed the CAT or St. George's Respiratory Questionnaire (SGRQ) and had their dyspnea assessed.

RESULTS

The study included 333 patients with mean age of 69 ± 9 years and smoking history of 38 ± 25 pack-years; 82% had ceased smoking. One-third suffered from cardiovascular comorbidities, 72% reported at least one exacerbation in the past year, and 82% recorded at least moderate health impairment (CAT scores ≥ 10 units). The CAT score was positively correlated with the SGRQ score (r = 0.72, P &lt; .001) and Medical Research Council (MRC) dyspnea score (r = 0.50, P &lt; .001) and poorly correlated with the FEV1 (r = -0.23, P &lt; .001) and number of exacerbations in the past year (r = 0.11, P = .04). The relationships between the CAT score and SGRQ score, MRC dyspnea score, or FEV1 did not differ between countries (P value for interaction term = 0.76, 0.75, and 0.06, respectively).

CONCLUSIONS

The CAT correlated well with the SGRQ and MRC dyspnea score in all countries, and the relationship did not differ between countries despite varying patient characteristics. This suggests that a CAT score in one of these countries has the same clinical significance as the same score in another.

Work-related respiratory symptoms and pulmonary function tests in northeast iranian (the city of Mashhad) carpenters

OBJECTIVE

To assess the respiratory symptoms and pulmonary function of carpenters from the city of Mashhad (northeast Iran).

METHODS

The frequency of respiratory symptoms was retrospectively estimated in a sample of 66 carpenters in the city of Mashhad in northeast Iran using a questionnaire including questions on work-related respiratory symptoms in the past year, allergy, type of irritant chemicals that induce respiratory symptoms, smoking habits, and working periods as a carpenter. PFT values were also measured in all participants, and the age and smoking habits matched those of a sample of men from the general population as a control group.

RESULTS

Thirty-five carpenters (53%) reported work-related respiratory symptoms. Cough (34.4%) and sputum (33.3%) were the most common symptoms, and only 15.15% of carpenters reported wheezing during work. All respiratory symptoms were higher in carpenters than in controls, which was statistically significant for cough and sputum (p<0.001 in both cases). Most allergic symptoms were also significantly greater among the carpenters than in the control group (p<0.05 for both itchy eyes and sneezing). Most respiratory and allergic symptoms in the carpenters increased during work compared to rest period which was statistically significant only for cough (p<0.05). PFT values were significantly lower in the carpenters than in control subjects (p<0.05 to p<0.001).

CONCLUSIONS

Carpentry work was associated with a high frequency of respiratory symptoms, particularly after exposure to irritating chemicals during work. PFT values were also significantly reduced among carpenters compared to controls.

Exposure to wood dust and its particle size distribution in a rubberwood sawmill in Thailand

A cross-sectional study on wood dust exposure and respiratory health effects was conducted at one of the largest rubberwood sawmills in Thailand. All workers (N = 340) from all jobs on a day shift were recruited for personal sampling. Overall, the personal inhalable dust (n = 742) and respirable dust (n = 241) of full-shift samples were collected from 27 job titles. These data were used to classify workers into high, moderate, and low exposure groups based on the concentrations found in each job. Static samples were also collected to determine the particle size distribution. Geometric means (GM) are used to present the concentrations of the rubber wood dust. Inhalable dust concentrations were clearly high, ranging between 0.2 to 59.4 mg/m3 and with GM of 4.7 mg/m3. The GM of inhalable dust in each job title enabled classification of the workers into three exposure groups: (1) high exposure; >5 mg/m3, (2) moderate exposure; 2.0-5.0 mg/m3, and (3) low exposure; 0.18-1.9 mg/m3. Among the high exposure group, the highest GM inhalable dust concentrations were found in sawing green lumber (12.8 mg/m3) and cutting dry lumber (7.3 mg/m3). The respirable dust concentrations were generally low, in the range of 0.1 to 6.0 mg/m3 with a GM of 0.5 mg/m3. The largest percentage of dust in major operations belonged to the thoracic fraction; 50% cutoff diameter was smaller than 9 mum. The size distribution of wood dust indicated a high proportion in the large particle sizes.

Inflammatory response and genotoxicity of seven wood dusts in the human epithelial cell line A549

Exposure to wood dust is common in many workplaces. Epidemiological studies indicate that occupational exposure to hardwood dusts is more harmful than to softwood dusts. In this study, human epithelial cell line A549 was incubated with well-characterized dusts from six commonly used wood species and from medium density fibreboard (MDF), at concentrations between 10 and 300microg/ml. After 3 and 6h of incubation, genotoxicity was assessed by measurement of DNA damage with the single-cell gel electrophoresis (comet) assay and inflammation was measured by the expression of IL-6 and IL-8 mRNA and by the amount of IL-8 protein. There was a 1.2-1.4-fold increase in DNA strand breaks after incubation with beech, teak, pine and MDF dusts compared with the levels in untreated cells, but after 6h only the increase induced by the MDF dust remained. Increased expression of cellular IL-6 and IL-8 mRNA was induced by all of the wood dusts at both times. Similar to IL-8 mRNA expression, the amounts of secreted IL-8 protein were elevated, except after incubation with oak dust, where a marginal reduction was seen. On the basis of the effects on IL-8 mRNA expression, the wood dusts could be divided into three groups, with teak dust being the most potent, MDF, birch, spruce and pine being intermediate, and beech and oak being the least potent. The induction of DNA strand breaks did not correlate well with the interleukin response. In conclusion, all wood dusts induced cytokine responses, and some dusts induced detectable DNA damage. The inflammatory potency seemed intermediate for dusts from the typical softwoods spruce and pine, whereas the dusts from species linked to cancer, beech and oak, were the least inflammatory. The variation of the effects induced by different wood dusts over time indicates that the DNA damage was not secondary to the cytokine response. Although hardwoods are often considered more harmful than softwoods by regulatory agencies, the current experiments do not provide evidence for a clear-cut distinction between toxicities of hardwood and softwood dust.

ROS-mediated TNF-alpha and MIP-2 gene expression in alveolar macrophages exposed to pine dust

BACKGROUND: Respiratory symptoms, impaired lung function, and asthma have been reported in workers exposed to wood dust in a number of epidemiological studies. The underlying pathomechanisms, however, are not well understood. Here, we studied the effects of dust from pine (PD) and heat-treated pine (HPD) on the release of reactive oxygen species (ROS) and inflammatory mediators in rat alveolar macrophages. METHODS: Tumour necrosis factor-alpha (TNF-alpha) and macrophage inflammatory protein-2 (MIP-2) protein release, TNF-alpha and MIP-2 mRNA expression, and generation of ROS were studied as end points after treatment of rat alveolar macrophages with PD or HPD. In a separate series of experiments, the antioxidants glutathione and N-acetyl-L-cysteine were included in combination with wood dust. To determine the endogenous oxidative and antioxidant capacity of wood dusts, electron spin resonance (ESR) spectroscopy was used. RESULTS: After 4 h incubation, both PD and HPD elicited a significantly (p < 0.05) increased mRNA expression of TNF-alpha and MIP-2 as well as a concentration-dependent release of TNF-alpha and MIP-2 protein. Interestingly, PD induced a significantly higher TNF-alpha and MIP-2 production than HPD. Moreover, a significantly increased ROS production was observed in alveolar macrophages exposed to both PD and HPD. In the presence of the antioxidants glutathione and N-acetyl-L-cysteine, the PD- and HPD-induced release of ROS, TNF-alpha, and MIP-2 was significantly reduced. Finally, electron spin resonance analyses demonstrated a higher endogenous antioxidant capacity of HPD compared to PD. Endotoxin was not present in either dust sample. CONCLUSION: These results indicate that pine dust is able to induce expression of TNF-alpha and MIP-2 in rat alveolar macrophages by a mechanism that is, at least in part, mediated by ROS.

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.