Coal–dirty and dangerous

The use of coal as a fuel is generally associated with the industrial revolution of 18th Century Britain, but coal was an important source of energy even in Roman times.

A century before the industrial revolution, many cities in England were dependent on coal for heating and for artisanal manufacturing. Air pollution was already a huge problem in the capital. In 1656, the English poet Sir William Davenport published a tract that complained about the ‘canopy of smoke’ that covered the city of London.  He even wrote a song that included the lines [1]:

London is smother’d with sulph’rous fumes
Still she wears a black-hood and cloak
Of sea-coal smoak..

A postcard from Widnes, Lancashire, circa 1930

The problem of air pollution in the capital was not really tackled until the mid-20th Century– after the ‘Great Smog’ of 1952 killed several thousand people. So for at least 300 years, the air pollution caused by the burning of coal in London was atrocious.

Coal is still a major source of primary energy—it was only knocked into 2nd place by oil in the mid-20th Century. Although its use as a fuel is declining in North America and Europe, it is increasing in Asia, and the production of coal is not expected to peak until after well after 2020.  In 2017, about 30 % of global primary energy production was being supplied by coal.

The miners and the mines

All mining operations are inherently dangerous. The list of catastrophic coal mine disasters that have occurred over the last 200 years is long and horrendous–but coal mining today is a lot safer. Even so, coal mining leads US industries in fatal injuries: the 2007 fatality rate in coal mining was almost 25 per 100,000 workers—more than six times greater than all private industry. In the US, employees in coal mining are more likely to be killed or to incur a non-fatal injury or illness, and their injuries are more likely to be severe, than workers in private industry as a whole [2]. But the situation has improved since then: in 2017, fatalities among US coal miners had dropped to 18 per 100,000 workers. It’s still a dangerous job.[3]

19th Ccentury coal mining in the black country, England

Progressive massive fibrosis (PMF) is an advanced, debilitating, and lethal form of coal workers’ pneumoconiosis. It is known as black lung disease, which gives you an idea of what it does to a miner’s lungs.  Breathing in coal mine dust is the sole cause of PMF in working coal miners. There is no cure.

One would think that, at least in the US with all the awareness of environmental issues and worker’s safety, that an occupational hazard of this type would have been eradicated by now.  In fact, the disease was almost eliminated 20 years ago with a reported prevalence of just 0.33% among active underground workers with at least 25 years of mining tenure.  Since that time, the incidence of the disease has risen substantially. For example, the Coal Workers Health Surveillance Program (CWHSP) reported in 2012 that the incidence of the disease in Kentucky, Virginia, and West Virginia had increased by a factor of ten [4].

The disease seems to be becoming more prevalent and more serious in the US.  A report released in February 2018, presented the results of surveys conducted at three clinics serving coal miners in Virginia, Kentucky, and West Virginia. A total of 416 cases of black lung disease were identified. Scientists have speculated that the increased incidence of the disease could be linked to the shift towards mining thinner coal seams that require cutting into the surrounding rock.  Silica dust from pulverized rock may damage lungs faster that coal dust alone [5] .  A few months later in July 2018, the US National Institute for Occupational safety and Health (NIOSH) reported that as many as one in five miners in central Appalachia suffer black lung disease, the highest rate in 25 years. Nationwide the condition now afflicts one in ten of miners, an increase of 3 % since 2012. [6]

In China in 2013, the government’s National Health and Family Planning Commission reported that there were 750,000 people suffering from black lung disease [7]

China has a huge air pollution problem

It’s not just the miners who suffer.  China, for example, has the largest number of premature deaths attributable to outdoor air pollution related to particulate matter—more than 1 million; followed by India with 620,000. In both cases, particulate emissions from coal combustion are reportedly a key underlying factor [8].  

The mining of coal has a massive and often irreversible impact on the environment. A form of surface mining called mountaintop removal, or MTR, involves stripping all trees from a mountaintop and blasting away the top of the mountain with explosives.  The resulting thousands of tons of debris is generally dumped into adjacent valleys, burying watercourses, totally disrupting watersheds, and often permanently changing the biodiversity of the area. In the US, in Appalachia alone, coalfields cover 48,000 km2 of mountaintops and valleys, displacing forests and polluting or burying more than 5% of the region’s streams [9].

Acid mine drainage

Drainage from coal mines is acidic, laced with heavy metals, and an environmental nightmare.  In the US, it has been described as one of the worst environmental problems facing the mining industry [10].  Acid mine drainage (AMD) is the acidic water produced when rock containing sulphide minerals, particularly iron pyrites, comes into contact with water and oxygen.  The chemistry is complex, but the result is that downstream watercourses are turned red, orange and yellow by the accumulating concentrations of ferrous compounds. The acidity of the water also dissolves other minerals from the rock: zinc, copper, arsenic, cadmium and lead. Left untreated the problem can last for centuries: some Roman mines in Britain still produce acidic drainage [11].

Prepping the coal

Before it is transported to power stations, coal is generally cleaned up to remove soil and other rock fragments. The preparation includes crushing the coal and removing extraneous non-coal materials. If the coal is high in sulphur or other impurities, it is washed with a water or immersed in a chemical bath to remove inorganic sulphur in the coal.

The process requires the application of complex chemicals, large quantities of water, and produces a thick slurry waste that may contain arsenic and mercury—which are both common in mined rock. This liquid waste is generally stored in huge surface impoundments, sometimes called tailing ponds, to prevent the pollution of local rivers and streams. While generally safe, they occasionally fail. Catastrophically.

In Inez, Kentucky, three coal mines owned by Martin County Coal Corporation fed coal into a preparation plant on conveyor belts through underground mine workings. Waste coal slurry from the plant was pumped into a 29 hectare tailing pond called the Big Branch impoundment.  The dam held back over 2 billion gallons of slurry.  

In October 2000, the dam failed, releasing about 300 million gallons of coal waste slurry into local streams, flooding stream banks to a depth of five feet. About 120 km of rivers and streams turned black, killing fish, and polluting the river water along the Tug Fork of the Big Sandy River, and some of its tributaries. Like all coal mine tailing ponds, the slurry contained detectable levels of arsenic, mercury, lead, copper and chromium.  Martin County Coal eventually paid out over $6 million in penalties and damages [12]

In 1972, the most destructive flood in West Virginia’s history occurred when a coal waste impounding structure collapsed on the Buffalo Creek tributary of Middle Fork. The failure released 132 million gallons of water. As a result of the flood, 125 people were killed, 1100 were injured and more than 4000 were left homeless [13].

While the regulations in the US and Canada are now much stricter, accidents still happen. In January 2018, it was reported that Duke Energy, one of the largest electricity companies in the US will pay an $84,000 penalty and work to stop potentially toxic waste from three North Carolina coal-burning plants from leaking into groundwater and nearby rivers.  Two dozen leaky spots were detected at coal ash pits before 2015.  Duke Energy acknowledged that the leaks into the Catawba and Broad rivers were from unlined earthen holding basins at the power plants. Groundwater in the vicinity may have been polluted, and Duke Energy has been providing hundreds of homes using wells within a half-mile of its coal plants with bottled water as a precaution. In January 2018, it was reported that some families had been using bottled water for over two and a half years.[14]

Canada has experienced similar dam failures at coal mines. On the night of Halloween 2013, an estimated 264 million gallons of waste coal slurry spilled out of a broken earth berm at the Obed Mountain mine near Hinton, Alberta. The burst contaminated 25 km of the Athabasca river. Ten municipalities were warned not to withdraw water from the river and to keep livestock away from the tainted water.[15] 

Apart from the slurry waste from the preparation process, solid wastes are generated in coal mines in substantial quantities. The piles of waste can be huge and, since they contain coal dust and fragments of coal, are prone to combust spontaneously. In the UK they are called coal slag heaps and were a dominant feature of the mining towns in Wales and the North of England when coal was a major industry in the last century.

The Aberfan tragedy

The Aberfan tragedy is still remembered. The Welsh mining village lies at the bottom of a small valley.  The Merthyr Vale coal mine, the mainstay of the local economy, was higher up the hill—where the colossal slag heaps dominated the skyline.

Mining in Aberfan started in 1869. Initially the waste was dumped in tips on the slope adjacent to the colliery. But as the volume of waste material increased, new tips were created on the slopes higher up the hillside.  By 1966, seven tips had been constructed. Tip number 7, the one that failed, held about 230,000 cubic metres of mine waste and had reached a height of 40 meters.

Just after 9 a.m., on October 21, 1966, after several days of rain, about half of the slag heap slid away, and over 100,000 m3 of mud and coal mine waste cascaded down onto the village below.  The mud and rubble roared down the valley, crashed through a row of small houses, and crushed the Plantglas junior school– where about 120 young children had just come into their classrooms. The slag heap slide killed 144 people: 116 children aged 7 to 10; six adults in the school including 5 teachers, and 22 people who were in the houses that were destroyed [19]. It was an appalling tragedy.

The village of Aberfan in Wales after the disaster. The slag heap, most of which slid down into the school, is in the background

Coal power

In 2017, the world production of coal was about 7.3 billion tonnes–over 40 % of which was mined in China (which imported even more). India and the USA each produced about 10% of the total. Not all coal goes into power production. A substantial fraction is used for the manufacture of steel and cement and other industrial and residential applications. In 2017, Canada produced 61 million tonnes of coal, of which 56% was metallurgical coal used for steel-making, and 44% was thermal coal used for generating electricity [20].

When coal is burned in a power plant to generate the steam that powers the turbines, the resulting mix of flue gases is a toxic cocktail of gas-phase chemical compounds and particulates.   

The main constituent is carbon dioxide—a gas which has little direct impact on human health, although it is the chief culprit when it comes to global warming.

But the other constituent gases have a noxious impact.  The table below adapted from a report published by Physicians for Social Responsibility, summarizes the health effects of the major power plant pollutants [21].

Power, pollution, and health

The PSR report sets out coal’s contribution to major health impacts as follows [22]:

Asthma. Nitrogen oxides, ozone, and particulate matter are all implicated in the prevalence of the disease.  The most vulnerable are children and adults.
Chronic Obstructive Pulmonary Disease (COPD). Emphysema with chronic obstructive bronchitis permanently narrows airways. In the US, COPD is the 4
th leading cause of death. Smokers are most vulnerable.  NOx and particulate matter are implicated.
Infant mortality. NOx and particulates are implicated in the deaths of infants less than 1 year old. Almost a quarter may have had respiratory causes
Lung cancer. Leading cause of cancer mortality in US among both men and women. The disease is exacerbated by air pollution caused by particulate matter
Acute myocardial infarction. Particulate matter is implicated in the disease

Coronary heart disease. CHD is a leading cause of death in the US and air pollution is known to negatively impact cardiovascular health.
Ischemic stroke. NOx, particulate matter and sulphur dioxide are all implicated in the prevalence of ischemic stroke.

Apart from the air pollution, there’s the ash.  You can’t burn coal without producing ash.

Coal ash

Coal ash is the waste that is left behind after coal is combusted in a coal-fired power plant. It includes fly ash, captured from smoke stack effluents, and coarser ash from the furnaces. The ash typically contains a slew of heavy metals including arsenic, lead, mercury, cadmium, chromium and selenium—all metals that are extremely toxic.

Coal ash pond in Georgia USA

Coal ash from power plants is generally dumped either into dry landfills or into wet surface impoundments. In the US, there are approximately 2000 coal ash dump sites across the country.

Across the US, roughly 100 million tons of coal ash are generated annually from power plants.  Coal ash is the second largest industrial waste stream in the US—second only to mine wastes.[23]

Wet ash ponds are just as liable to fail as the impoundments and tailing ponds at the coal mines themselves.  The most notorious incident occurred in December 2008 when an earthen wall holding back a large coal ash disposal pond at the coal-fired power plant in Kingston, Tennessee, failed catastrophically.  The 16 hectare pond spilled more than 1 billion gallons of coal ash slurry into the adjacent river valley, covering about 1200 hectares of land with a thick, viscous, toxic sludge. The spill destroyed three homes, damaged several others, and contaminated the Emory and Clinch rivers.

When the EPA tested water samples after the spill, they found toxic heavy metals including arsenic—which they measured at 149 times the allowable standard for drinking water. The water also contained lead, thallium, barium, cadmium, chromium, mercury and nickel.[24]

It took workers a year to clean up the mess—during which time they could not avoid breathing in the toxic coal ash dust. Coal ash dust is highly toxic—many of those workers subsequently became ill. The contaminated area was finally designated a Superfund site by the US Environmental Protection Agency. [25]

Under a 2015 US EPA coal ash rule, all US electric generating utilities were required to analyse groundwater pollution at each of their operating coal ash dumps by the end of January 2018 and publish their results one month later. Initial results showed that a majority of the coal ash pits are leaking polluted water into groundwater [26].

In March 2019 it was reported that 90 percent of coal plants in the US had contaminated nearby groundwater resources. The survey covered 242 coal-fired power plants. A majority of these plants reported unsafe levels of at least four different toxins [33].

But there’s one other dangerous pollutant that is widespread in the environment, present in the human tissue of practically every man and woman on the planet, and whose toxic neurological effects are mainly due to the burning of coal: mercury.[27]

So to recap: coal is a filthy fuel. It’s mining, preparation, processing, transport, and combustion causes more harm and environmental damage than any other source of energy. It is the primary source of greenhouse gases. It is high time its use as a fuel was simply banned across the globe. There are many alternative sources of energy that are much cleaner and much less harmful for people and the planet.


For more information check out these sources:

[1] See the brilliant book by Geoffrey Parker: Global Crisis: War, climate change, & catastrophe in the seventeenth century. Yale University Press, New Haven, USA. 2013.
[2] See the US Bureau of Labor Statistics Fact sheet | coal mining| April 2010. Injuries, illnesses and fatalities in the coal mining industry, at //
[3] See statistics from the US Mine Safety and Health Administration, accessed at : //
[4] See the article in the American Journal of Respiratory and Critical Care Medicine: Resurgence of debilitating and entirely preventable respiratory disease among working coal miners.  AJRCCM, Vol 190, No.6, September 15, 2014.
[5] See: New black lung epidemic emerging in coal country, at //  Also: Black lung study finds biggest cluster ever of fatal coal miners’ disease.  At: //
[6] See: Congress is giving the coal industry a break, and sick miners may pay the price. Accessed at: //
[7] See : Coal miners suffering from black lung disease fight for compensation. //
[8] See the report :  Energy and Air Pollution. World Energy Outlook special report. International Energy Agency 2016. Page 35.
[9] See the article by the Union of Concerned Scientists: How coal works.  Accessed at : //
10] See : Technical Document : Acid mine drainage prediction.  US Environmental Protection Agency, Office of Solid Waste, Washington. DC. 1994.
[11] See: Acid mine drainage –a legacy of an industrial past. At //
[12] See: The Inez coal tailing dam failure (Kentucky, USA). //
[13] Coal waste impoundments: Risks, responses and alternatives. National Academy of Sciences, Washington DC.
[14] See: This is a first: Duke Energy agrees to pay $84K penalty for coal ash leaks.  //
[15] See: Did Canada just have the largest coal slurry spill in its history? Accessed at: // largest-coal-slurry-spill-in-its-history-1881814153.html  
[16] See : Ponds are the biggest environmental disaster you’ve never heard of//, and Tailing pond spill: what happens to effluent over time  //
[17] See: Report on Mount Polley tailing storage facility breach. At : //www.mountpolleyreviewpanel/default/files/report/ReportonMountPolleyTailingStorageFacilityBreach.pdf. The breach was avoidable.  The report stated bluntly : “Had the downstream slope in recent years been flattened to 2.0 horizontal to 1.0 vertical, as proposed in the original design, failure would have been avoided.” (emphasis added).
[18] See: Many coal sludge impoundments have weak walls, federal study says. Accessed at:   //

[19] See: Remembering Aberfan. Institute of hazard, risk and resilience blog, Durham University UK.  //
[20] See Natural Resources Canada : Coal facts.  Accessed at: // 
[21] See: Coal’s assault on human health. A report from Physicians for Social Responsibility. 2009. //
[22] See: Coal’s assault on human health, pages x, xi.  Op. cit.
[23] See: Coal ash: The toxic threat to our health and environment, Physicians for Social Responsibility and Earth Justice, 2010. //
[24] Ibid.
[25] See: , at //
[26] See: New industry data confirms toxics are polluting groundwater at coal ash sites.  At : //
[27] See the page on this website