# The impact of occupational hazards in coking plants on the incidence of hypertension—a longitudinal study

## TL;DR

This study finds that workers in coking plants, especially in chemical and coal preparation workshops, have a higher risk of developing hypertension compared to logistics workers.

## Contribution

The study provides new evidence linking occupational exposure in coking plants to increased hypertension risk using longitudinal data and Cox regression analysis.

## Key findings

- Hypertension incidence density was highest in coal preparation and coking workshops.
- Coking workshop workers had the highest hypertension risk (HR = 1.822) after controlling for confounding factors.
- Disease-free survival varied significantly across workshops (p < 0.05).

## Abstract

To explore the incidence density and risk of hypertension among employees in different workshops of a coking plant.

The research subjects were employees of a coking plant in western Inner Mongolia. Based on inclusion and exclusion criteria, we studied 448 employees hired between 2011 and 2023. Of these, 285 were front-line workers exposed to occupational hazards, while 163 were second-line workers with lesser or no exposure. We collected data on the general demographic characteristics, systolic blood pressure, diastolic blood pressure, and other information of the research subjects, calculated the incidence density of hypertension, and used the Cox proportional hazards regression model to analyze the association between exposure to occupational risk factors and the risk of hypertension.

During the observation period, we identified 229 cases of hypertension, with an incidence density of 11,187.10 per 100,000 person-years. The average age of the patients was 42.33 ± 8.24 years, and the average working duration was 3.57 ± 2.84 years. The number of new cases in logistics, coal preparation, chemical production, and coking workshops were 53, 45, 47, and 84, respectively, with incidence densities of 7,019.83, 14,469.45, 12,737.13, and 13,725.49 per 100,000 person-years, respectively. The risk of hypertension in coal preparation, chemical production, and coking workshops was 4.061, 3.364, and 2.427 times higher than that in logistics workers, respectively. Cox regression analysis showed that, after controlling for gender, age, smoking, drinking, and other factors, the risk ranking of hypertension in each workshop was as follows: coking workshop (1.822) > chemical production workshop (1.752) > coal preparation workshop (1.622). The log-rank test revealed that the differences in disease-free survival distribution among workers in different workshops were statistically significant (p < 0.05).

The study shows that the incidence density of hypertension among employees in the chemical industry, coking, and coal preparation workshops after joining the company is significantly higher than that in the logistics group, and the risk of incidence is relatively higher (HR = 1.622–1.822 after controlling for confounding factors). Long-term exposure of coking plant workers to related environments increases the risk of hypertension.