Respiratory Symptoms and Pulmonary Function Among Male Steel Workers in Terengganu, Malaysia

Background and Context

Workers in the steel and iron production industry are exposed to a complex mixture of metal dusts and fumes that can adversely affect the respiratory system. The inhalation of particulate matter containing iron oxide, silica, chromium, cobalt, nickel, and other metallic compounds has been linked to a range of respiratory disorders, including chronic bronchitis, occupational asthma, pneumoconiosis, and chronic obstructive pulmonary disease (COPD). The severity of these effects depends on the composition, concentration, and duration of exposure, as well as individual susceptibility factors including smoking status and pre-existing respiratory conditions.

Malaysia’s steel industry, while smaller than those of major steel-producing nations, employs thousands of workers in production facilities concentrated primarily in the eastern coast of Peninsular Malaysia. Despite the well-established respiratory hazards of the steel industry, relatively few studies had examined the respiratory health of Malaysian steel workers at the time of this research. This cross-sectional study was conducted in a steel factory in Terengganu to determine the relationship between dust exposure and pulmonary function in male steel workers.

Study Design and Methods

The investigation employed a cross-sectional design among male workers in a steel production plant in Terengganu. Participants were recruited from various work categories within the facility, encompassing the range of exposure levels present in the iron and steel making process. The study included two principal assessment components: spirometric testing to measure pulmonary function parameters, and detailed personal interviews using a structured questionnaire adapted from the British Medical Research Council (BMRC) Questionnaire on Respiratory Symptoms.

The BMRC questionnaire captured information on the presence and frequency of specific respiratory symptoms including morning cough, morning phlegm production, shortness of breath, chest tightness, and wheezing. Sociodemographic data, occupational history (including job category, duration of employment, and previous occupational exposures), smoking status, and medical history were also collected. Spirometric testing measured Forced Vital Capacity (FVC), Forced Expiratory Volume in 1 second (FEV1), and the FEV1/FVC ratio. Data were analysed using SPSS, with chi-square tests for bivariate associations and multiple regression models to identify independent predictors of respiratory symptoms and pulmonary function decline.

Key Results

The study revealed a high prevalence of respiratory symptoms among the male steel workers. Morning phlegm was the most commonly reported symptom, affecting 33.1 per cent of workers, followed by shortness of breath (31.9 per cent), chest tightness (30.4 per cent), and morning cough (17.8 per cent). These prevalence rates are substantially higher than would be expected in the general population and are consistent with the respiratory irritant effects of metal dust exposure.

Statistical analysis revealed that age and duration of employment were the factors most significantly associated with the presence of respiratory symptoms. Older workers and those with longer tenure in the steel industry were more likely to report respiratory complaints, reflecting the cumulative nature of dust exposure effects. This finding is consistent with a dose-response relationship between occupational dust exposure and respiratory health deterioration.

Spirometric testing demonstrated that FEV1 values were significantly reduced among the steel workers compared to predicted values based on age, height, and sex for a healthy Malaysian reference population. This reduction in FEV1 indicates airflow obstruction, which is a hallmark of dust-related respiratory disease. The FEV1 decline was more pronounced in workers with longer employment duration, further supporting the dose-response relationship.

Extended Research Context

This study was part of a broader programme of research by the same investigative team examining metal dust exposure and respiratory health in Terengganu’s steel industry. A subsequent companion study published in the Iranian Journal of Public Health reported on metal dust exposure measurements and their relationship to respiratory health, finding that mean trace metal dust concentrations (time-weighted average over 8 hours) for cobalt and chromium exceeded occupational exposure prescribed values in most work units. The prevalence rates in the companion study were broadly consistent: chest tightness at 28.0 per cent, chronic phlegm at 26.8 per cent, and shortness of breath at 24.1 per cent. Smoking status and cumulative respirable metal dust exposure were both negatively associated with FEV1 values. A further study by the same group established a clear exposure-response relationship between cumulative metal dust exposure and deterioration in lung function values, reinforcing the need for improved control measures.

Implications for Occupational Health

The findings have direct implications for occupational health management in Malaysia’s steel industry. The high prevalence of respiratory symptoms and measurable lung function decline among workers indicate that existing dust control measures are insufficient to protect respiratory health. Specific recommendations include improving engineering controls such as local exhaust ventilation and wet suppression systems to reduce airborne dust concentrations; ensuring proper and consistent use of appropriately rated respiratory personal protective equipment; implementing regular respiratory health surveillance including spirometry for all exposed workers; and enforcing compliance with occupational exposure limits for metal dusts, with particular attention to cobalt and chromium, which exceeded permissible limits.

The significant associations with employment duration underscore the importance of career-long monitoring and the need for longitudinal studies to track respiratory health trajectories over time. Workers who develop early signs of respiratory compromise should be identified through screening and considered for reassignment to lower-exposure roles.

Limitations

The cross-sectional design limits the ability to establish causal relationships or assess temporal patterns of lung function decline. The healthy worker effect—whereby individuals who develop severe respiratory problems may leave the industry, leaving behind a relatively healthier workforce—may have led to underestimation of the true respiratory impact of steel dust exposure. The study did not include environmental exposure measurements alongside clinical assessments (this was addressed in the companion study), and self-reported symptom data are subject to reporting bias. The single-factory study design limits generalisability to other steel production facilities with different processes, dust compositions, or control measures.