Occupational Health Risk Assessment Of Industrial Dust In A Coal Mine And Study On Its’ Effect On Pulmonary Function And Abnormal Chest Radiograph

Industrial dust from coal mining processes can cause serious respiratory damage.Determination of industrial dust level and assessment of its’health risk are essential to prevent respiratory health damage in coal miners.The practice of health risk assessment in China started late.The national occupational health standard“Classification of Occupational Disease Hazards in the Workplace”was implemented in 2010,and it is still unclear how effective it is in actual health risk assessment of coal dust and whether it is consistent with internationally used methods such as the International Council on Mining and Metals（ICMM）occupational health risk assessment method and the Australian occupational health risk assessment method.Previous studies on coal workers’pneumoconiosis are numerous,but there is insufficient research on early health damage to the respiratory system due to coal dust such as abnormal changes in chest radiography or lung function.In this study,a large state-owned coal mine was selected to conduct health risk assessments based on the measurement of industrial dust in the workplaces and to compare the differences between different methods.Meanwhile,Cumulative dust exposure（CDE）was calculated by combining the occupational history and previous data on dust concentration in the enterprise to explore its’association with lung function and abnormal chest radiography.Part 1.Exposure assessment and occupational health risk assessment of industrial dust in a coal mineObjectives:To compile the concentration and variation of industrial dust in the main positions of the coal mine,and use different methods to assess health risk and compare the similarities and differences of the methods.Methods:Collecting the monitoring data of respirable dust in this coal mine since 2013 and conducting an on-site measurement of industrial dust according to the national standard for determination of dust in workplaces.The occupational health risk assessment of coal dust was conducted by using China’s occupational health standard“Classification of Occupational Disease Hazards in the Workplace”,ICMM,and the Australian Occupational Health Risk Assessment Methods,respectively.Spearman correlation analysis was used to assess the correlation between risk ratios of different methods.Results:1.The results of self-measurement of respirable dust concentration from 2013 to 2020suggested that the dust concentration exceeded the occupational exposure limit in most years for the positions of continuous miner driver at the digging face and coal miner driver at the coal mining face.The results of on-site dust measurement showed that the dust was coal dust in nature and had a high dispersion.The total dust concentration in the main positions in the workplaces ranged from 0.45 to 61.78 mg/m³,with an overall qualified rate of 45.8%according to the occupational exposure limit.The concentration of respirable dust in the main positions ranged from 0.10 to 13.32 mg/m³,with an overall qualified rate of63.6%.2.The results of multiple assessment methods showed that coal miner drivers and frame support workers had the highest health risk level.The number of highest hazard operations evaluated by China’s method was lower than foreign methods,and the risk levels of the ICMM matrix method were higher than the other methods generally.The results of correlation analysis showed that the risk ratios of all methods were strongly correlated with each other,all P<0.05.Conclusions:The exceedance of dust concentration in the underground coal mining and digging face was serious.Risk levels of coal mining machine drivers and frame support workers were high.The Chinese dust classification method was generally in consistency with the ICMM and Australian assessment methods.Part Ⅱ:Effects of coal dust on lung function and abnormal chest radiographyObjective:To explore the Effects of coal dust on lung function and abnormal chest radiography.Methods:Socio-demographic information and anthropometric indicators about 1294 male employees of this coal mine mentioned above were collected using questionnaires and physical examinations.CDE was calculated by combining occupational history and historical monitoring data.Forced Vital Capacity（FVC）,Forced Expiratory Volume in One Second（FEV₁）,and Maximum Mid-expiratory Flow（MMF）were measured using lung function spirometers.The posterior-anterior chest radiographs of the subjects were taken by digital X-Ray radiography.The generalized linear model was used to analyze the association between CDE and lung function indexes.Univariate and multiple logistic regression models were used to assess the influencing factors of abnormal chest radiographs.Results:1.The mean age of the study population was 35.3 years old and the mean length of service was 13.3 years.The percentages of smokers were 64.14%.The generalized linear model showed that CDE was negatively associated with FVC,FEV₁,FEV₁/FVC,and MMF（P<0.05）.2.The prevalence of abnormal chest radiographs gradually increased with increasing CDE(P _trend<0.05).Both univariate and multifactorial logistic regression models showed that CDE,age at first job,length of service,body mass index（BMI）,and smoking were risk factors for abnormal chest radiograph.High annual household income and education were protective factors for abnormal chest radiograph.No change in the prevalence of restrictive ventilation dysfunction with increasing CDE was found(P _trend>0.05).Conclusions:FVC,FEV₁,FEV₁/FVC,and MMF were negatively associated with CDE.The prevalence of abnormal chest radiographs gradually increased with increasing CDE.