The results showed that the direct effect coefficient of CE was 0.132, which is significant at a 1% level, indicating that CE had an obvious positive effect on LIR. Our results are consistent with previous research. There was an increasing evidence that cardiopulmonary was affected by potential factors from burning sources of air pollution sources. Akbari et al. (Akbari 2019)came up with a mechanism about how fossil fuel emissions induce cancer. The results showed that ROS-induced mitochondrial damage (as the main power generators of human cells) can induce cancer via a reduction in cellular adenosine triphosphate, leading to genetic instability. Hosgood et al. (Hosgood 2010) pooled seven studies from North America, Europe, and Asia to test solid-fuel use and lung cancer risk and found an association between lung cancer and coal use in Asia. Shang et al. (Shang 2010) indicated that the increase in air pollution would increase the overall mortality rate of cardiovascular and cerebrovascular diseases. Both laboratory and epidemiological studies have strongly indicated that carbon emissions had a negative impact on the incidence rate of lung cancer.
In addition, the direct effect coefficient of UR was 0.425, which is significant at the level of 1%, which showed that UR had an obvious positive effect on LIR. With the economic development, China's urbanization and industrialization are accelerating (Wang 2015). In 2010, the urban population in China reached 670 million, accounting for nearly 50% of the total population (China Statistics Press 2013). Industrialization and urbanization have brought about a large amount of consumption of fossil fuels, especially the consumption of coal, and the average energy consumed by urban residents is almost three times that of rural residents, which has brought serious climate challenges and air pollution to cities and their surrounding areas(Qi 2013). In addition, the large amount of energy consumption has led to increase combustion of fossil fuels, which is considered as the main source of urban air pollution(Wang 2016;Zhang 2016).
The results of Moran’s I indicated that there was a positive spatial correlation between the LIR and CE in China from 2013 to 2015. Although the indirect influence coefficient of all the variables was not significant at the level of 10%, which indicated that CE had no impact on the LIR of its surrounding areas. In total effect coefficient of CE was 0.005 and was significant at a 1% level, which pointed out that the average effect of a change in CE in a certain region is on LIR in all regions. Therefore, the research results indicated that there are geographical differences in carbon emissions but there is no spatial spillover effects. Geographical location is also a key factor that determine carbon emissions. In some northern cities, such as Tianjin, Jinan, Tangshan, and Taiyuan, carbon emissions were relatively high due to the large amount of coal production in the surrounding areas and the heating policy in the north (Wang 2019). In 2010, per capita carbon dioxide emissions in northern cities of China reached 10.2 tons, which was 54% higher than in southern cities of China, partly due to the use of fuels, for heating during the cold season, especially coal (Shen 2017).
In the TFE, the coefficients of CE were positive at the 10% significance level, which pointed out that CE exposure had a long-term impact on LIR from 2013 to 2015. In addition, the Pearson test implied that CE in the period has the greatest effect on Chinas LIR in 2015, and the lag period was about 17 years. Lung cancer was the result of the long-term exposure to environmental factors. Qu et al. analyzed the short-term, and long-term relationship between energy consumption, environmental pollution and public health in China from 1985 to 2014, and found that the proportion of coal consumption, smoke and dust emissions, and other effects on cardiovascular and respiratory diseases are significantly positively correlated in the short and long term (Qu 2017). This suggested that a long-term effort was needed to reduce the impact of carbon emissions on lung cancer rates.
Since 2013, China has drawn on the advanced experience of carbon emission control in the United States, Europe, and other countries, and selected seven provinces and cities, including Beijing, Tianjin, Shanghai, Chongqing, Shenzhen, Hubei, and Guangzhou (2016, and Fujian was added in 2015) to carry out pilot projects and implement a series of carbon emission reduction measures. Currently, 31 provinces (autonomous regions and municipalities directly under the central government) in China have adopted strict carbon emission regulations and other measures(Yongbin 2008). Therefore, adopting policies to reducing carbon emissions will have a positive impact on health.