云南省宣威市是我国肺癌最严重的地区，该区肺癌发病率和死亡率均居世界首位。对宣威肺癌患者的基因组学研究发现，宣威肺癌具有与众不同的基因特征，是一种与环境相关的独特发病模式。通过综述宣威肺癌的流行特征以及燃煤排放物的污染水平和毒理学特征，并结合二叠纪末期C₁煤层的地球化学特征探讨宣威肺癌的地质起因。宣威肺癌主要流行特征表现在，肺癌死亡率男女比接近1.22，女性肺癌死亡率明显偏高。前人研究表明，室内燃煤排放颗粒物的长期、高浓度暴露，是宣威肺癌的主要诱因。综述毒理学研究结果可知，宣威室内燃煤排放颗粒物中的重金属、多环芳烃和微晶石英矿物浓度均高于其他地区，且被证实可能会引起更严重的DNA损伤和细胞破坏。通过对比宣威肺癌死亡率的空间分布和不同煤矿的煤层分布发现，可采煤层包含C₁煤的来宾和龙场地区同时也是宣威肺癌的高发地区，推断C₁煤的燃烧可能与宣威肺癌高发有关。C₁煤作为晚二叠世最后一层煤，成煤期间受二叠纪−三叠纪生物大灭绝事件影响，形成了独特的地球化学特征。高含量的重金属、多环芳烃和微晶石英矿物等潜在致癌物不仅存在于C₁煤中，也随着室内燃煤被释放到空气中，并通过呼吸系统进入人体体内，破坏细胞及DNA结构，造成肺阻塞、肺炎等一系列呼吸道疾病，严重的可能导致肺癌发生。

Xuanwei City in Yunnan Province is the area struck by the most severe lung cancer in China, with the incidence and mortality of lung cancer ranking first in the world. The study of genomics of lung cancer patients has shown that lung cancer in Xuanwei City has distinctive genetic characteristics and a unique incidence mode related to the environment. This study reviewed the epidemiological characteristics of the lung cancer epidemic in Xuanwei, as well as the level of pollution and toxicological characteristics of emissions from coal combustion. Moreover, this study discussed the geological origins of the lung cancer epidemic in the city by combining the geochemical characteristics of coal seam C₁ formed at the end of the Permian. The epidemiological characteristics of the lung cancer epidemic in Xuanwei are as follows: (1) The mortality ratio of male to female patients approximates to 1.22, indicating a significantly higher mortality rate of female patients; (2) From 1973 to 2016, the lung cancer mortality exhibited a trend of first increase and then decrease, and the areas with a high incidence of lung cancer constantly expanded. Previous studies proposed that a major predisposing factor of lung cancer in Xuanwei City is long-term exposure to high-concentration particulate matter emitted from indoor coal combustion. As shown by the review of toxicology studies, compared to other areas, the particulate matter emitted from indoor coal combustion in Xuanwei City contains higher concentrations of heavy metals, polycyclic aromatic hydrocarbons, and microcrystalline quartz minerals, which have been confirmed to be able to induce more severe DNA damage and cell destruction. As indicated by a comparison of the spatial distribution of the lung cancer mortality and the distribution of coal seams in different coal mines in Xuanwei City, the Laibin and Longchang coal mines, where the recoverable coal seams contain coal seam C₁, are areas with a high incidence of lung cancer. Therefore, it can be inferred that the high incidence of lung cancer in Xuanwei may be related to the combustion of coals from coal seam C₁. As the last coal seam of the Late Permian, coal seam C₁ was subjected to the Permian-Triassic mass extinction event during its coal formation, forming unique geochemical characteristics. In addition to occurring in coals from coal seam C₁, potential carcinogens including high concentrations of heavy metals, polycyclic aromatic hydrocarbons, and microcrystalline quartz minerals are also released into the air along with indoor coal burning and enter the human body through the respiratory system. As a result, they damage cells and DNA structure and cause a series of respiratory diseases, such as lung obstruction, pneumonia, and even lung cancer.