Coal Combustion: Air Pollutants And Their Impact

Burning coal releases a number of airborne toxins and pollutants, including mercury, lead, sulfur dioxide, nitrogen oxides, particulates, and various heavy metals. These pollutants have been linked to asthma, breathing difficulties, brain damage, heart problems, cancer, and neurological disorders. They also contribute to global warming and climate change, with carbon dioxide (CO2) being the primary greenhouse gas produced from burning coal and other fossil fuels. In 2022, coal-fired power plants in the US emitted about 19% of the country's total energy-related CO2 emissions. Aside from CO2, other significant pollutants released from burning coal include methane, sulfur trioxide, and mercury, which can have detrimental effects on both human health and the environment.

Mercury and other heavy metals

Mercury is a dangerous neurotoxin that is released into the atmosphere when coal is burned. It can stay airborne for over a year and travel to remote ecosystems, especially in the Arctic Circle. Mercury can contaminate land, oceans, and streams, and is converted into methylmercury, which can accumulate in the bodies of animals and humans. Methylmercury can cross the blood-brain and placental barriers, and exposure is associated with neurological and cardiovascular damage, endocrine disruption, and an increased risk of diabetes. It is particularly dangerous for children, as it can impact brain development.

Coal-fired power plants are the largest source of mercury pollution, and mercury emissions from these plants have significant local and global impacts. People living near these plants bear a disproportionate burden of mercury pollution, and communities across the country are affected due to mercury's ability to travel. Mercury emissions from coal-fired power plants have been linked to health issues such as asthma, cancer, heart and lung ailments, and neurological problems.

In addition to mercury, coal burning releases other heavy metals into the atmosphere, including lead, arsenic, chromium, and nickel. These heavy metals are toxic and can have harmful effects on human health and the environment.

To reduce mercury and heavy metal emissions, the U.S. Environmental Protection Agency (EPA) has implemented regulations such as the Mercury and Air Toxics Standards (MATS) and the Clean Air Act. However, many power plants continue to emit large quantities of mercury and other pollutants, and stronger safeguards are needed to protect public health and the environment.

Relatively inexpensive technologies, such as activated carbon injection, can help lower mercury and heavy metal emissions from coal-burning power plants. Additionally, reusing and recycling waste produced from burning coal can reduce environmental impacts, and land previously used for coal mining can be reclaimed for other purposes.

Sulfur dioxide and acid rain

Burning coal releases airborne toxins and pollutants, including sulfur dioxide, which is a major contributor to acid rain. Acid rain is caused by the formation of sulfuric and nitric acids in the atmosphere, which then fall to the ground mixed with rain, snow, fog, or hail. This phenomenon has negative consequences for the environment, including harm to plants, wildlife, and water bodies.

Sulfur dioxide (SO2) is a byproduct of burning coal and is one of the main contributors to acid rain. SO2 and nitrogen oxides (NOx) can be carried over long distances by winds, allowing acid rain to affect areas far from the sources of these emissions. This makes acid rain a widespread issue, not just a local problem for those living near power plants or industrial facilities.

Acid rain usually has a pH level between 4.2 and 4.4, which is significantly more acidic than normal rain, which typically has a pH of around 5.6 due to the presence of naturally occurring carbonic acid. The lower pH of acid rain can have detrimental effects on the environment, particularly aquatic ecosystems, as it can cause water bodies to become too acidic for aquatic life to survive.

To mitigate the issue of acid rain, some electric power plants have installed scrubbers, or flue gas desulfurization equipment, to reduce the amount of sulfur emitted through their smokestacks. Additionally, the coal industry has developed methods to reduce sulfur and other impurities from coal before it is burned, and some consumers have transitioned to using low-sulfur coal. These efforts have helped to reduce the environmental impact of acid rain, but more work is needed to address the issue fully.

The effects of acid rain on the environment are complex and far-reaching. It can harm vegetation, buildings, and water bodies, and can have negative consequences for aquatic life, insects, and fish. The accumulation of acidic particles and gases on surfaces can be washed off by rainfall, causing acidic water to flow over the ground and potentially contaminating water sources. This can lead to ecological imbalances and negatively impact the health of ecosystems and wildlife.

Nitrogen oxides and smog

Nitrogen oxides (NOx) are a group of highly reactive gases that include nitrogen dioxide (NO2), nitrous acid, and nitric acid. They are formed through the combustion of fossil fuels such as coal, oil, methane, and diesel at high temperatures. NOx gases are also produced naturally by lightning and contribute to air pollution, particularly in areas with high motor vehicle traffic.

Nitrogen dioxide is a significant component of NOx and is considered an indicator for this group of nitrogen oxides. NO2 is primarily released into the air through the burning of fuels, with the largest sources being trucks, buses, cars, and power plants. When NO2 is formed indoors, it is typically due to the burning of fuels like wood or gas in appliances such as stoves, dryers, or space heaters.

Breathing air with high concentrations of NO2 can irritate the airways and aggravate respiratory diseases, especially for those with pre-existing conditions such as asthma. Prolonged exposure to elevated levels of NO2 may even contribute to the development of asthma and increase susceptibility to respiratory infections.

Nitrogen oxides are a precursor to smog formation, which is a significant issue in states like California. Smog is particularly harmful to children, individuals with lung diseases, and those who work or exercise outdoors, as it can cause damage to lung tissue and reduce lung function. The presence of NOx also contributes to the formation of acid rain and affects tropospheric ozone levels.

To address the issue of NOx emissions, the Clean Air Act has implemented more protective standards, leading to cleaner power plants, industrial sites, and vehicles. As a result, nitrogen dioxide emissions have decreased, and air quality has improved nationwide. However, there is still work to be done to ensure that fewer people are exposed to unhealthy levels of nitrogen dioxide pollution.

Particulate matter and lung disease

Burning coal releases a number of airborne toxins and pollutants, including particulate matter. Particulate matter, also known as particle pollution or soot, is a mix of tiny solid and liquid particles that are in the air we breathe. These particles vary widely in size, shape, and chemical composition and may contain inorganic ions, metallic compounds, elemental carbon, organic compounds, and compounds from the Earth's crust.

Particulate matter is one of the six widespread air pollutants for which there are national air quality standards to limit their levels in outdoor air. These standards are necessary because particulate matter has been linked to a range of adverse health effects, particularly for those with heart or lung diseases. Research has shown that long-term exposure to particulate matter can lead to premature death, especially in people with chronic heart or lung diseases. It can also cause reduced lung function growth in children and increase respiratory symptoms such as irritation of the airways, coughing, or difficulty breathing.

The Children's Health Study found that children living in communities with high levels of particulate matter had slower lung growth and smaller lungs at age 18 compared to children in low-level areas. Additionally, particulate matter has been associated with increased mortality from all causes, including cardiovascular disease, respiratory disease, and lung cancer. Those living near emission sources, such as power plants, industrial sites, and vehicles, are at a higher risk of exposure to particulate matter.

The Clean Air Act has helped drive down emissions contributing to particulate matter, and air quality has improved nationwide. However, many people still live with unhealthy levels of particle pollution, and fine particles can be carried over long distances by wind, affecting even those not near emission sources.

Carbon dioxide and global warming

Carbon dioxide (CO2) is a colourless, odourless gas produced by human activities such as the burning of fossil fuels and cement manufacturing, as well as by natural processes like volcanic eruptions and wildfires. It is a greenhouse gas, meaning it helps to trap heat in the atmosphere, similar to how a glass greenhouse traps heat inside. This makes carbon dioxide a significant contributor to global warming and climate change.

CO2 is released into the atmosphere when coal is burned, as coal is primarily made up of carbon molecules. The combustion of fossil fuels, including coal, is the main driver of global warming. In 2022, CO2 emissions from burning coal for energy accounted for about 19% of total US energy-related CO2 emissions and 55% of total CO2 emissions from the electric power sector. Human activities, such as burning fossil fuels, have increased atmospheric CO2 levels by 50% in less than 200 years, leading to a significant rise in global temperatures.

The increase in atmospheric carbon dioxide due to human activities is unprecedented in the planet's history. The last time CO2 levels were this high was during the Mid-Pliocene Warm Period, approximately 3 million years ago, when global temperatures were 2.5-4 degrees Celsius higher than pre-industrial times. Sea levels were also significantly higher, at least 16 feet and possibly up to 82 feet higher than in 1900.

If the current trends continue and global energy demand is met primarily with fossil fuels, carbon dioxide emissions could reach 75 billion tons per year or more by the end of the century. This would result in atmospheric CO2 concentrations of 800 ppm or higher, which hasn't been seen on Earth in almost 50 million years. The consequences of such high CO2 levels would be severe, including intensified global warming, rising sea levels, increased frequency and severity of droughts, heat waves, heavy rainfall, and storms, as well as species loss.

To mitigate these impacts, it is essential to transition to cleaner sources of energy and implement carbon capture and storage technologies to reduce CO2 emissions from coal-fired power plants.

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