Pneumoconiosis is the most widely distributed occupational disease worldwide. China is currently the largest coal producer and consumer and the country with the most coal miners and cases of coal workers' pneumoconiosis (CWP). Despite more than 70 years of effort, the problem of CWP and silicosis remains serious. There is a lack of analysis of direct data on coal miners’ pneumoconiosis from all over the country. This study aimed to describe the epidemiology of coal miners’ pneumoconiosis and reveal some important clues regarding its social determinants. The annual incidence rate, 20-year prevalence rate, and incidence rate of coal miners’ pneumoconiosis per million tons in China from 1949 to 2021 were calculated by using the data of annual number of coal miners’ pneumoconiosis diagnosed and reported from the coal mining and dressing industry, the number of coal miners, and the raw coal production, and the relationship between the incident cases of coal miners’ pneumoconiosis and the death toll from coal mine safety accidents was analyzed using Pearson correlation analysis, with the aim of exploring the relationship between the incident cases of coal miners’ pneumoconiosis and its social determinants with an ecological study. From 1949 to 2021, there have been more than 462,000 patients with coal miners’ pneumoconiosis in China, showing double U-shaped distributions with an increasing trend, accounting for about 50.5% (462,000/915,000) of all diagnosed pneumoconiosis in China, while the incidencet rate of coal miners’ pneumoconiosis presents a large W shaped distribution with three peaks over a time span of more than 50 years. From 1949 to 1986, there was a strong correlation between the incident cases of coal miners’ pneumoconiosis and raw coal production, the number of coal miners, and the number of deaths from coal mine accidents (r = 0.849, P < 0.001; r = 0.817, P < 0.001; r = 0.697, P < 0.001, respectively), but there was no such correlation found from 1987 to 2006. It was estimated that the annual incidence rate of coal miners’ pneumoconiosis in China from 2016 to 2020 was 3.4‰ (95% CI: 2.6–4.3‰), and the prevalence rate across the recent 20-year observation period was 4.8% (95% CI: 4.6–4.9%), both measured at the peak or around the peak over the 70 years. In particular, 1963, 1986, 2006, and 2009 were the four important turning points in time. There was a sustained high level of incident cases of coal miners’ pneumoconiosis with double U-shaped curve in China, which may be affected by a variety of social determinants and risk factors.

What is already known on this topic? Asbestos is classified as a Class I Carcinogen by the International Agency for Research on Cancer (IARC) because exposure causes mesothelioma and lung cancer in addition to asbestosis and plaques. So far, asbestos has been banned in 67 countries, but chrysotile, a commonly encountered form of asbestos, is still widely used in China and most developing countries. Most asbestos-caused cancers are not reported, recorded, and compensated in many countries. What is added by this report? Enterprises manufacturing asbestos products have been migrating from economically developed Eastern China to relatively underdeveloped central and western regions between 2010 and 2019. Asbestosis cases reported in Tianjin, Beijing, Shandong, Xinjiang, Gansu, Qinghai, and Sichuan accounted for a large proportion of the total cases in China, which was inconsistent with the distribution of asbestos-related enterprises (AREs). The reported asbestosis cases versus total pneumoconiosis cases declined from 2.81% to 0.39% from 2006–2017, and this proportion reached 0.69% in 2018. What are the implications for public health practice? Robust occupational and environmental health assessments and reporting are needed to define the epidemiology of asbestos-related lung diseases, and management of using asbestos and existing products containing asbestos need strengthening and follow-up. Enterprises should be encouraged to use safer substitutes and gradually ban asbestos materials in China.

Long-term inhalation of welding fume at high exposure can cause welder’s pneumoconiosis, and metals in welding dust are associated with respiratory dysfunction. This cross-sectional study, which contains 384 Chinese male workers who were or had been working in a container factory, aimed to assess the potential risk of haemal and urinary metal content in welder’s pneumoconiosis. Further, we investigated their effects on lung function parameters. Metal content and lung function were measured using inductively coupled plasma–mass spectrometry (ICP-MS) and spirometer, respectively. The concentration and metal content of respirable dust as well as total dust were collected at this container factory. Lung function of cases with welder’s pneumoconiosis was significantly worse, as indicated by lower values of FVC, FVC% predicted, FEV1, FEV1% predicted, MEF25% predicted, and MMEF% predicted (p < 0.05). Results of logistic regression models showed that haemal Cr and Zn were risk factors of welder’s pneumoconiosis (OR = 4.98, 95%CI: 1.73–21.20, p = 0.009 for Cr; OR = 5.23, 95%CI: 1.56–41.08, p = 0.033 for Zn) after adjusted with age, BMI, working years, welding dust exposure years, and smoking status. Multiple linear regression models showed that several metals (haemal Cd and Pb; urinary Cd and Fe) were significantly associated with different lung function indices in the welder’s pneumoconiosis group. Compared to non-welders, welders were exposed to considerably higher levels of respirable dust, total dust, and six kinds of metals (p < 0.05). In conclusion, haemal Cr and Zn are positively related to welder’s pneumoconiosis. Meanwhile, Cd and Pb might worsen lung function in welder’s pneumoconiosis.