China mining accidents

 The risk for coal-mining accidents in China is one of the highest in the world. According to a 2003 government report, the coal miners' death rate per one million population was about 37 times that of America's coal-mining death rate.1,2 However, to date there has been no epidemiologic analysis of nationwide coal-mining accidents reported in the literature. We used eight years of published national coal-mining accident data to analyze the patterns and characteristics of coal-mining accidents. The results are intended to provide useful information to evaluate the safety of coal mines and formulate specific prevention measures.

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METHODS

Data

The study data were derived from China's national coal-mining safety accident report, released by the State Administration of Coal Mine Safety from January 1, 2001, through December 31, 2008.1 The project team spent approximately one year extracting, completing, and analyzing the data, which included 9,037 accidents reported from 30 provinces, municipalities, and autonomous regions of China, with a total of 23,418 deaths and 2,498 related injuries.

Analysis

After extraction, the data were transformed into a Microsoft® Excel database. We performed analyses on the frequency of accidents and the number of related deaths by percent distribution, secular trend, type of accident, mortality (per one million population), and geographic distribution. We analyzed the data using Chi-square tests.

We calculated the annual mortality rate of coal-mining accidents per one million population as the annual number of deaths related to coal-mining accidents divided by the national population of China (estimated to be 1.3 billion from recent national census data) times one million. We calculated the annual mean number of deaths per coal-mining accident as the annual number of deaths related to coal-mining accidents divided by the annual number of coal-mining accidents.

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RESULTS

We found a dramatic decline in both coal-mining accidents and deaths since 2006 (Figure 1), with a significant difference in the changes over time (χ2=55.17, p<0.05). The mean mortality rate per year was 2.25 per one million population. In recent years, coal-mining accident mortality rates have declined, while the mean number of deaths per accident has increased (Figure 2).

Figure 1.

Number of coal-mining accidents and deaths in China, by year: 2001–2008

Figure 2.

Mortality rate of coal-mining accidents and mean number of deaths per accident in China, by year: 2001–2008

Coal-mine collapse was responsible for the highest frequency of deaths from 2001 to 2008 (n=4,653). Table 1 shows that collapse and machinery caused significantly more accidents and deaths than did other types of coal-mining incidents (χ2=39.83, p<0.05). The number of accidents caused by collapse and machinery declined in the last years, as did the number of accidents caused by nearly all coal-mining incidents. Furthermore, collapse and machinery declined in percentage of accidents.

Table 1.

Type of coal-mining accidents in China by year, 2001–2008

Gas explosions contributed to the highest number of deaths (n=8,013). From 2001 to 2008, there were seven gas explosions, each of which caused more than 100 casualties. Table 2 shows that gas explosions and collapses were associated with the majority of deaths, and that deaths associated with these causes declined starting in 2006.

Table 2.

Number of deaths by type of coal-mining accident in China, by year: 2001–2008

As shown in Table 3, gas explosion accidents were the most severe in terms of numbers of fatalities per accident. In the past eight years, the country reported that 80% of fatal coal-mining accidents, which caused more than 30 deaths, were mostly due to gas explosions, and collapse had the highest frequency in all coal-mining accidents.

Table 3.

Severitya of coal-mining accidents (n=9,037) in China by type of accident, 2001–2008

aSeverity was measured by the number of deaths per accident.

There are currently about 12,777 coal mines in China. Figure 3 shows coal-mining accidents and deaths in relation to their geographic distribution. There are more than 1,000 coal mines in the provinces of Yunnan, Sichuan, Shannxi, Hunan, and Heilongjiang, and the coal-mining accident death rates in these provinces are significantly higher than in other provinces.

Figure 3.

Geographic distribution of coal-mining accidents in China, 2001–2008a

aProvinces where coal-mining accidents were significantly higher than other provinces

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DISCUSSION

In China, there appears to have been a decrease both in coal-mining accidents and deaths since 2006. This decline can be attributed to efforts by the Chinese government to improve the country's coal-mining safety. Facing a severe coal-mining safety situation, the State Council has issued a series of regulations to strengthen the surveillance of coal-mining safety. To intensify efforts in work safety supervision, the State Administration of Production Safety has been promoted to be the General Administration of Production Safety, and the State Administration of Coal Mine Safety has been put under its jurisdiction. As part of this move, local governments are assigning people to supervise the work safety of collieries and all coal mines to ensure that they strictly abide by safety production standards. China's Premier, Wen Jiabao, typically convenes special safety meetings to work on measures to improve work safety in coal mines, where major accidents involving high casualties and economic losses have occurred with alarming frequency in the past years. Three billion Yuan ($36 million U.S.) has been devoted to technological renovation on coal-mining work safety—gas management in particular—at major state-owned coal mines.

However, to meet the needs of rapid economic growth and the rising demands for coal, the Chinese coal-mining industry has dramatically increased its production since 2006. The recovery of the price of coal at domestic and international coal markets is also driving the economic interests of coal mines. Some mines have become preoccupied with overproduction and neglected safety. As a result, several serious safety concerns persist, including: (1) a severe shortage of safety professionals, especially technical personnel with college-level training in safety production; (2) the accumulation of safety hazards from years of overproduction and lack of corresponding investments in safety measures; (3) the complex mining conditions for many coal seams and increasing difficulty in preventing the outburst of coal and gas, as well as water leakage, after years of exploration and expansion of the production field; and (4) the lack of management, appropriate planning, and an occupational safety system among small, private coal mines.

Gas released during coal mining is primarily composed of methane, which, when mixed with coal dust, can dramatically increase the intensity of an explosion. The incomplete reaction of coal dust can also release poisonous gases, thereby resulting in more casualties and property losses. Our results indicated that higher priority should be given for the prevention and control of these two types of accidents. Historically, to prevent major gas accidents, the government often sent safety supervision teams to major coal mines with serious gas problems and invited colliery safety experts to evaluate safety situations in coal mines with the potential for dangerous explosions and formulate specific prevention measures. In China, great attention is generally paid when any accident causes more than 10 casualties. Our study identified a high occurrence of accidents resulting in eight or nine deaths. In a total of 382 accidents, more than nine deaths were reported.3 Given their large social impact and generally serious economic losses, these accidents should be the focus of prevention and control efforts. Chinese authorities need to work hard to improve their performance and promote best practices by identifying inconsistencies in coal-mining accident death reporting in the future.

China had 28,000 coal mines at the end of 2005, of which 2,000 were state-owned. Because the number of coal-mining fatalities is unacceptably high, particularly due to the number of unregulated small coal mines, Chinese authorities had closed 12,209 unsafe small coal mines by the end of 2008, leaving only 12,777 regulated coal mines. Hainan Province is the only region that reported no coal-mining accidents. Sichuan Province, Hunan Province, and the Chongqing municipal area reported the highest numbers of coal-mining accidents, and the provinces of Guizhou, Hunan, and Shanxi reported the highest number of deaths caused by coal-mining accidents. These statistics may be related to the natural coal production conditions in these provinces, which generally bear many risk factors. The design and production process does not align with the geological structure in many mines, which inevitably leads to future disasters. This risk is further confounded by out-of-date mining technology and lack of investment in safety production among local private coal mines. It is exacerbated by the unbanned, destructive, and predatory exploitation that has caused the destruction of the normal coal structure, as well as the lack of a strong, effective coal-mining safety monitoring and inspection system.

Limitations

This study had several limitations. Prior to 2000, reports of coal-mining accidents generally lacked accurate information on accident statistics. Therefore, there may be serious selection and information bias.4 The published literature related to coal-mining safety in China has been limited to a few mines or work-related injuries.5 To the best of our knowledge, there are no nationwide statistics on coal-mining accidents. In this study, the data were taken from the National Bureau of Coal Mine Safety and covered all 30 provinces, municipalities, and autonomous regions in China during an eight-year period. As such, there may have been some selection and information bias. But, according to the report entitled “Report, Investigation, and Handling of Production-Related Accidents,” which was drafted by the State Council in China on April 9, 2007, it is required that any accidents occurring during production and business activities that result in personal injury or economic loss should be investigated by the government agency that is in charge of the oversight of production safety,6 and that the results of this investigation shall be reported and made public. Therefore, the reliability level of the data used in this study was reasonably accurate as an appropriate epidemiologic term.

Reports related to coal-mining accidents from other countries are also scarce. For some comparison, the U.S. Centers for Disease Control and Prevention (CDC) reported the frequency of underground coal-mining accidents and related mortality rates in the U.S. from 1900 to 2006. The report shows that U.S. coal miners' deaths per 200,000 hours of work was 0.04.2 Data on China before 2000 were not readily available. Before 2000, reports of coal-mining accidents generally lacked accurate information on accident statistics. Even so, China lags far behind developed countries in terms of coal-mining safety, as statistics on deaths per one million population show that Chinese miners are dying at a rate that is about 37 times the rate of America's coal-mining fatalities. In European countries such as Russia, Poland, and the Ukraine, coal-mining accidents were reported more often than in other European countries,7–9 showing that coal mining remains a very hazardous industry worldwide.

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CONCLUSIONS

Although the Chinese government has made great efforts to increase coal-mining safety, and the number of deaths has decreased since 2006, the death rate and the total number of coal-mining deaths are still very high. The risk for coal-mining accidents in China is still one of the highest in the world. Accident prevention is critical and should be strengthened. China needs to effectively integrate scientifically based safety protection measures into the production process. The National Mining Medical Center is responsible for conducting emergency medical care according to the guidelines of the National Emergency Preparedness Plans for Industrial Safety Accidents as well as the Mining-Related Disaster Medical and Emergency Rescue Plan. Our results may provide useful information to help improve prevention and control measures for coal-mining safety in the future.