Power plants using coal are known for producing greater quantities of carbon emissions than other forms of energy.
Earlier this week, President Obama unveiled the US Environmental Protection Agency's (EPA) Clean Power Plan, aiming to reduce carbon dioxide emissions by 32% from the level they were at in 2005 over the next 15 years.
"We can choose to believe that Superstorm Sandy, and the most severe drought in decades, and the worst wildfires some states have ever seen were all just a freak coincidence," says Obama. "Or we can choose to believe in the overwhelming judgment of science - and act before it's too late."
This will entail a shift in how America generates its energy. Power plants are the largest source of carbon emissions in the US, producing around one third of the country's greenhouse gas pollution, and so many will need to change their methods of energy production to make them cleaner.
The main focus of this policy is to address the threat of climate change, yet the move is likely to have public health implications as well. In June, a report published in The Lancet described climate change as a "medical emergency" and the fight against climate change as the greatest global health opportunity of the century.
Indeed, while the US military has described the impacts of climate change as "already accelerating instability in vulnerable areas of the world and are serving as catalysts for conflicts," it is the impact on public health that could be seen as the most significant outcome of the plan's implementation.
With all this in mind, this Spotlight will examine the impact of different energy sources on public health. Is coal as harmful as is made out? Is what is good for the health of the planet equally good for the health of the public?
Bad news for coal, good news for lungs?
It has been widely regarded that the coal industry will be hardest hit by changes brought about by the proposed plan, and many industry officials and states dependent on coal mining are already gearing up to challenge the policy.
However, power plants powered by coal are estimated to produce twice the amount of carbon pollution that is produced by plants using natural gas.
Carbon pollution has long been recognized as harmful to health, and the White House has made significant claims about how reducing these emissions will have an impact on improving public health.
The Natural Resources Defense Council estimate that American power plants emit more than 2 billion tons of carbon dioxide into the atmosphere every year. This drives temperature increases and rises levels of smog - a mixture of pollutants - in the air that can cause asthma and make the lungs more susceptible to infection.
While carbon dioxide makes up 82% of greenhouse gas emissions in the US, power plants also emit methane and fluorinated gasses, although these are produced in more significant quantities elsewhere, such as in agriculture.
Not only does air pollution directly cause illness but it can indirectly increase the risk of several health conditions. Rising temperatures - one consequence of air pollution - can expand the reach of vector-borne diseases and increase the risk of more intense and frequent extreme weather events, such as heatwaves, floods and droughts.
Last year, the World Health Organization (WHO) reported that 1 in 8 deaths worldwide in 2012 were attributable to air pollution. In terms of diseases linked to outdoor air pollution, WHO stated that 40% of deaths were due to ischemic heart disease, 40% were due to stroke and 11% were due to chronic obstructive pulmonary disease (COPD).
"Excessive air pollution is often a byproduct of unsustainable policies in sectors such as transport, energy, waste management and industry," says Dr. Carlos Dora, WHO coordinator for public health, environmental and social determinants of health.
As coal is recognized as the foremost producer of carbon emissions in the US, it would appear that it could have the biggest impact on public health out of all sources of energy, and thus a move toward other methods of energy production is well-advised.
Recent studies indicate potential risks with fracking
In 2012, coal supplied 37% of the electricity used in the US. In comparison, 30% was produced by natural gas, 19% by nuclear sources, 7% by hydropower sources and 5% by renewable sources.
Although natural gas power plants do not produce as much carbon pollution as coal-powered plants, they are not without their problems. Coal mining is estimated to produce 10% of the US's methane emissions, while natural gas and petroleum systems produce 29%.
In fact, the Energy Justice Network state that natural gas is worse for global warming than coal due to the amount of methane that is produced - methane is more potent at heating the atmosphere than carbon dioxide.
The process of hydraulic fracturing, or fracking, to extract natural gas has rapidly become more common in recent years.
They cite a report from 2013 conducted by the International Panel on Climate Change that found methane's global warming potential over 20 years as 86 times worse than that of carbon dioxide.
In recent years, many studies have also suggested that there are a number of health problems associated with a method of gas drilling that is growing in popularity. Hydraulic fracturing, commonly known as fracking, has received much scrutiny from researchers and some of the results have not been positive.
Over the past year, Medical News Today have reported on several studies that have observed links between the process of fracking - breaking open rock formations to release gas by injecting a mixture of water, salt and chemicals - and negative health outcomes.
The wastewater from the fracking process has been suggested to contaminate drinking water downstream from fracking sites.
Pennsylvania has seen a dramatic increase in the amount of fracking in recent years due to it housing the Marcellus Shale Deposit - one of the biggest natural gas fields in the world (which also spreads to West Virginia, Ohio and New York). Before 2007, only 44 gas wells were drilled on this formation. Between 2007-2010, this number rose to 2,864.
Unsurprisingly, many studies on fracking have been conducted in this state.
One team of researchers has observed that increased levels of the carcinogen radon in homes in Pennsylvania have corresponded with the construction of fracking wells. Another study carried out in Pennsylvania found that areas more densely populated with fracking sites also had higher rates of hospitalization.
Recently, a study examining the proximity of pregnant women to fracking sites found that women living closest to wells using fracking could be more likely to have babies with lower birth weights than those living farther away.
Although a lot of these studies are observational and as such cannot prove any causation between fracking and these health problems, they do suggest that gas also may not be the healthiest source of energy available.
Nuclear and renewable sources of energy
There are a wide range of alternatives to fossil fuels available, however, that do not produce anywhere near the level of carbon emissions as more popular sources like coal and gas. But do they have problems of their own?
Nuclear power plants provided the third largest proportion of America's electricity in 2012. Its supporters state that its use reduces greenhouse gas emissions and saves on resources in transport, handling and extraction as it requires less fuel to create more energy.
Wind turbines are considered to be a clean source of energy as they do not produce any pollution.
However, nuclear reactors and the preparation of nuclear fuels are believed to release radioactive materials into the surrounding air and water. It takes a long time for nuclear waste to lose its radioactivity and subsequently its health risks, meaning that waste products must be carefully disposed of or stored to avoid contaminating the environment.
Supporters of nuclear power state that the amount of radiation that the public is exposed to from nuclear power plants is minuscule in comparison with natural sources of radiation. The World Nuclear Association report that while the nuclear industry is the source of 1% of radiation exposure, 85% comes from natural sources.
In contrast, the Energy Justice Network state that many studies have associated increases in the risk of cancers and infant mortality among people living near nuclear reactors. One study reported that levels of a radioactive pollutant called strontium-90 were found to be 30-50% higher in the baby teeth of children in close proximity to nuclear plants.
Modern nuclear disasters at Chernobyl and, more recently, Fukushima in Japan, have shown that when problems occur at nuclear reactors, the consequences can be far-reaching. Recently, MNT reported on a study that suggested mental illness could be the biggest risk from nuclear accidents.
Although the dangers of nuclear power continue to be debated, there is less uncertainty surrounding renewable sources of energy. Solar power, wind power and hydropower use various natural sources to generate power and do not burn any fuels.
Hydropower utilizes dams to channel the movement of water to produce electricity. Although they do not directly produce air emissions, decaying vegetation in the lakes created by hydropower dams produces methane that plays a role in global warming.
Solar and wind power do not burn any fuels and do not cause pollution. The use of these sources of energy is what is hoped will drive the reduction in carbon emissions proposed by the Clean Power Plan and subsequently bring about the benefits to public health that the White House has identified.
While critics question whether or not these forms of energy will be able to meet the needs of the general public - both in terms of power and economics - it is unquestionable that switching to these sources of energy will prevent the range of different health problems that are caused both directly and indirectly by other power sources.