Pulmonary function in Tyre factory workers in Central Kerala, South India

Introduction:The workers involved in tyre manufacturing are exposed to a mixture of chemicals and dusts which could potentially lead to respiratory obstruction and/ or restriction.Objective: To estimate the prevalence of respiratory dysfunction due to occupational exposure in a tyre manufacturing factory.Methods: A cross sectional study was conducted in a major tyre manufacturing factory in Kerala.Two hundred and ninety six workers were interviewed from mixing plant, tyre plant, tube plant and pre-cured tread rubber (PCTR) plant, and administrative staff of a tyre factory.Pulmonary function test was done using a portable spirometer.Regression equations were calculated using SPSS for windows using normal population data from 51 healthy people.Fifth percentile of these parameter values were taken as lower limit of normal (LLN) adjusted for age and height.Respiratory dysfunction of either restrictive or obstructive nature was estimated based on these values in the tyre workers.Results: The duration of work exposure ranged from 1.6 to 37.4 years.A significant 53.7% of the workers complained of breathlessness.35.5% of the workers were smokers.The proportion of individuals with obstructive disorder was 4.4% and that of restrictive disorder was 54.1%.Tube plant had higher proportion (60.3%) of workers with respiratory dysfunction.However, the tyre plant, where the duration of employment was the shortest among the various sections, had 50% of the workers having respiratory dysfunction.Smoking habits and family history did not significantly explain the presence of abnormality of pulmonary function.LLN method was found better correlated with respiratory problems than conventional method of fixed percentage of predicted values.Conclusion: Rubber tyre making is associated with high prevalence of respiratory dysfunction which in majority of cases, are subclinical.Regular spirometry assessment can detect individuals at risk of problems and they could be better educated about regular protective mask usage which is currently not enforced.