Epidemiological Evaluation of Temporal Disparity in Pulmonary Functions amongst Coke Oven Employees in Bokaro Steel Plant

Abstract

Chronic exposure to high concentration of coal dust, in acute hot and humid working environment at Coke Oven (CO) Battery in Bokaro Steel Plant leads to significant temporal changes in pulmonary functions amongst the employees. Periodic health check-up (PHC) records of majority of the employees, clearly indicates the causal relationship of temporal reduction in all parameters of Spirometry specifically in FVC, FEV1, PEF, FEF25-75% and FMFT. On the contrary, in spite of working in the same environment over a period of time, a significant number of Coke Oven workers' pulmonary records indicate 'No' or negligible changes (p<0.01). To understand such disparity, a planned study was designed. Initially, 634 Coke Oven employees' pulmonary data were retrieved based on their presence in the master roll both in 1992 and 2012. Considering FVC as a key indicator of dust related dysfunction, 20 lowest FVC% (Group -I) as well as 20 highest FVC% (Group 2) data were selected from the retrieved data. The mean age (years), height (centimeters) and BMI (kg/m2) of Group -I were correlated with Group .2 and no significant difference were observed between the two groups (p> 0.1). Surprisingly, high significant differences were observed both in FVC% [(56.4±7.91 in Gr.1) and (97.3±4.81 in Gr.2)] & FEV1% [(48.35±13.20 in Gr.1) and (95.25± 4.34 in Gr.2)] between the two groups (p<0.001) in spite of their same occupational exposure to dust & smokes. No significant associations were observed between temporal disparity in PFT and alcoholism, nutritional status and other socio-cultural parameters. Till date, author does not have any logical explanation regarding temporal irreversibility of pulmonary functions amongst a significant group of employees, who are equally exposed to severe dust hazards over a specific time period. Individual susceptibility or personal body resistance in a normally distributed population may not be simple answer of such differences. Advanced physiological research in this respect may open up new vistas in occupational health scenario in future.