Are mines in the United States getting safer in the last 20 years?

miners — Miners waiting to work at the Virginia-Pocahontas Coal Company Mine #4 near Richlands, Virginia (Creative Commons).

Accidents and safety issues have long been major concerns in the mining industry, especially in sub-surface mining. From gas ignition, rock falls to dealing with explosives, accidents of a wide variety of causes killed over 900 miners in the United States since 2000.

Created in 1977 under the U.S. Department of Labor, Mine Safety and Health Administration (MSHA) is responsible for enforcing mandatory safety standards. This project uses datasets avilable from MSHA to delve into accidents, injuries and fatalities reported by mine operators and contractors across the country from a chronological and geographical perspective, asking the question: Are mines in the United States getting safer in the last 20 years?

The first graphic shows how the number of mining accidents in the country changed from 2000 to 2017 on a monthly basis.

The circular heatmap offers a general overview and treats accidents of different severity more or less the same. The calendar heatmap below documents all 857 fatalities reported by mine operators and contractors since 2000 and offers more context on accidents that caused multiple fatalities.

The most deadly accident during this time frame is the 2010 coal dust explosion at a mine in Raleigh County, West Virginia, which killed 29 miners in total, making it the country’s worst mine disaster in four decades. According to MSHA's report released the year after, flagrant safety violations contributed to the explosion.

MSHA can declare mines with a history of major safety violations as having a pattern of violations (POV), which allows the agency to increase regulatory scrutiny at that particular mine after the disaster in West Virginia.

Fifty-one mines were identified as at risk of being given a POV notice in 2010. In order to have the POV designation removed, the mine must receive a full inspection with no serious and substantial violations according to the Federal Mine Safety and Health Act of 1977.

In 2006, the Mine Improvement and New Emergency Response Act of 2006, also known as the MINER Act, amended the previous legislation to require emergency response plans in underground coal mines, new regulations on sealing of abandoned areas and enhanced civil penalties. Signed by President George W. Bush, the MINER act is the most significant mine safety legislation in 30 years.

Although the previous two heatmaps offer context chronologically, it's difficult to tell whether the mines are actually getting safer without calculating a variable reflecting accident occurrences for each individual mine. Below is a bubble map identifying U.S. mines with high rate of accidents from 2002 and 2017 and how the numbers fluctuate among different mines across the time frame.