All posts by Mark Shepherd

About Mark Shepherd

I work in the environmental movement helping to protect the air we breathe, the water we drink, the land that sustains us and the natural and biological resources we depend on.

Vaquita Capture Program Ends

Vaquita Rescue Program Setback
Vaquita (Phocoena sinus), a small porpoise endemic to the northern Gulf of Mexico. Illustration by Justin Shepherd
Vaquita (Phocoena sinus) Illustration by Justin Shepherd

A  rescue program to save the vaquita, the world’s most endangered cetation (whales, dolphins and porpoises), has not started off well.  Earlier this year, I reported that there were only an estimated 30 vaquitas left in the world. That number may now be down to 15 or less.   The ambitious program to save vaquitas experienced a setback when a captured female died.

Continue reading Vaquita Capture Program Ends

The Most Painful Stings

Fire Ants (solenopsis invicta)

Painful stings leave an impression. Everyone who has ever been stung has a story to tell.  Some of the stories of painful stings include common characters, such as honey bees (Apis melifera).  Being stung by a bee is fairly common, but unless you are allergic to them, your story is comparable to a common children’s tale: most people have read it, but can only vaguely remember how the story goes.  Continue reading The Most Painful Stings

Are Insect Populations Declining?

On a recent trip to research insect populations, I visited a small sliver of the Chihuahua desert that runs through the extreme southeast corner of Arizona, I encountered hundreds of eager hover flies.  I say eager, because the flies followed and buzzed around me relentlessly.  While I couldn’t identify any single individual fly, I am certain that a few of them followed me for more than half a mile as I trekked through the dry, rock strewn, dusty desert.  I am not a dancer, but all of the swatting, arm waving, and stumbling probably made me look like I move like Mic Jagger.  Relief came when wind from an approaching thunderstorm forced the flies to land or be blown away. Continue reading Are Insect Populations Declining?

Vaquita: The World’s Rarest Marine Mammal Is In Trouble

Vaquita (Phocoena sinus), a small porpoise endemic to the northern Gulf of Mexico, Illustration by Justin Shepherd
Vaquita (Phocoena sinus), a small porpoise endemic to the northern Gulf of Mexico. Illustration by Justin Shepherd

Another species of marine mammal is on the verge of extinction.  The Vaquita (Phocoena sinus), a small porpoise endemic to the northern Gulf of Mexico, is reportedly just 30 individuals away from being lost forever.  The name vaquita is Spanish for “little cow,” and it looks somewhat like a panda mixed with a dolphin.   Because individuals suffer high mortality when trapped in illegal gill nets used by fishermen, the vaquita populations have plummeted since 1997.  Mexico has spent millions trying to stop the illegal practice of using gill nets, but to date has not been able to prevent it completely. Continue reading Vaquita: The World’s Rarest Marine Mammal Is In Trouble

Killing Poachers

Wild greater one-horned rhinoceros (Rhinoceros unicornis) standing by a forest track in Kaziranga National Park, Assam, India. Park wardens on bicycles in the background. Photo by Jeremy Richards;
Wild greater one-horned rhinoceros (Rhinoceros unicornis) standing by a forest track in Kaziranga National Park, Assam, India. Park wardens on bicycles in the background. Photo by JeremyRichards

Many are familiar with the worldwide effort to stop the illegal hunting of endangered wildlife.  Some nations have created wildlife refuges where hunting is limited, while other nations, such as Costa Rica, have banned hunting altogether.  Creating a refuge is challenging enough, but enforcing hunting limitations is far more difficult.  Even in the well protected reserves in Africa, poachers still manage to kill threatened elephant and rhinoceros. Continue reading Killing Poachers

Protecting Elephants

In October of 2016, in what was considered a surprising move, the United States, the European Union and several African nations voted against an all-out ban of the elephant ivory trade;
African Elephant in Kenya Photo by Kevin Lings

In October of 2016, in what was considered a surprising move, the United States, the European Union and several African nations voted against an all-out ban of the elephant ivory trade.  It was a surprising move in that there was strong support in favor of a ban from the countries hosting the two largest elephant ivory markets: the United States and China. Continue reading Protecting Elephants

Haleakala Flightless Moth

haleakala flightless moth final
Haleakala flightless moth (Thyrocopa apatela). Photo by Mark Shepherd

Many species in the Hawaiian islands are known to be endemic (found nowhere else).   An example is the Haleakala flightless moth. This moth is not just restricted to the Hawaiian Islands, but it can only be found on the windswept western slopes of the summit of Haleakala volcano.  Its scientific name is Thyrocopa apatela.  It is, however, more commonly known as the Haleakala flightless moth or the Haleakala grasshopper moth. Continue reading Haleakala Flightless Moth

The Still Mysterious Case of Missing Bees

Honey Bee (genus Apis) foraging in the field. Photo by Mark Shepherd
Honey Bee (genus Apis) foraging in the field. Photo by Mark Shepherd

We are just four months shy of the 10-year anniversary when David Hackenberg reported losing two-thirds of his bee hives to a phenomenon now known as Colony Collapse Disorder (CCD).   It was in October of 2006 that Mr Hackenberg, a Pennsylvania bee keeper, noticed that 2000 bee colonies he had transferred to Florida to pollinate crops were devoid of almost all adult bees, except the queen.  Continue reading The Still Mysterious Case of Missing Bees

Diversity among Some Environmental Organizations

A review of board members and executives at several large and well known environmental organizations finds little diversity in leadership positions.
African American Hiker Photo by Mark Shepherd

If the biological world exhibited a similar diversity in the number of species present that several environmental organizations do with regard to minorities in positions of leadership, it would be an extremely impoverished world.   I reviewed the online list of board members and executives at several large and well known environmental organizations, and was very surprised to find that there is very little diversity in leadership positions, and almost no African Americans.  There were only a few Hispanics, Asians, and at one prestigious environmental organization, there were no African Americans.  That’s right, not one! Continue reading Diversity among Some Environmental Organizations

Monk Parakeet Populations Growing


Three Monk Parakeets perched and interacting in a tangle of branches (Buenos Aires);
Three Monk Parakeets perched and interacting in a tangle of branches (Buenos Aires).
Photo by Rich Lindie

In 1939, nearly 77 years ago, the Carolina Parakeet (Conuropsis carolinensis) was declared extinct.  At the time, it was United States’ only known native parrot.  The cause for its extinction is not certain, but is frequently reported to be the result of deforestation.  Some experts, however, believe deforestation and hunting may have reduced the populations sufficiently to allow other factors, such as disease, to be the proximate cause of extinction.  Continue reading Monk Parakeet Populations Growing

Green Sea Turtle (Chelonia mydas)

Photo by Willyam Bradberry

Green Sea Turtle (Chelonia mydas)

AKA: Pacific green turtle, black (sea) turtle

Green Sea Turtle (click on this link to watch)

While diving off the coast of Hawaii, I encountered multiple green sea turtles in the shallow areas around the shore.  Adult green sea turtles are primarily vegetarians and feed on sea grass and algae.  Juvenile turtles are reported to eat crabs and jellyfish, in addition to sea grass and algae. Continue reading Green Sea Turtle (Chelonia mydas)

What are the Health Risks Associated with Fossil Fuel Power: How Much Do You Know?


In the United States, there are approximately 6,997 power plants with a capacity to generate at least one megawatt of electricity (United States Energy Information Agency [EIA], 2013). Each of these power plants may operate one or more electric power generators resulting in an estimated 19,023 individual generators (EIA, 2013). It is estimated that U.S. power plants produced 3.8 billion kilowatt-hours (KWh) of electricity in 2013 (EIA, 2014). Plants combusting fossil fuel (coal, oil, natural gas) supplied approximately 66% of the U.S. electrical energy needs, nuclear power plants provided 19% and renewable energy plants provided another 13% (EIA, 2014).

The public health risks associated with power plants are largely dependent upon pollutants released from the fuel used to generate heat. The primary pollutant emissions from coal combustion include particulate matter, nitrogen oxides, sulfur oxides, carbon monoxide, methane, carbon dioxide, mercury, volatile organic compounds (VOCs), and heavy metals (United States Environmental Protection Agency [EPA], 2013). Natural gas-fired plants also emit nitrogen oxides, carbon dioxide and methane, but in lower quantities than coal-fired power plants. Sulfur oxides and mercury emissions from natural gas combustion are negligible (EPA, 2013a). Nuclear power plants and renewable power plants do not have emissions from combustion; however, nuclear plants discharge large quantities of high temperature water used for cooling. In addition, nuclear power plants generate nuclear waste that is difficult to dispose and remains hazardous for thousands of years (Chapman, 2012).

Here I focus on risks associated with fossil fuel power generation; however, it is important to recognize that risks occur along the entire fuel cycle, from resource extraction to waste disposal. The public and occupational health risk from nuclear power generation is primarily related to radiation exposure during all stages of the fuel cycle (Hamilton, 2011). Secondary health risks include trauma (Hamilton, 2011). Among five renewable energy categories (geothermal, hydropower, photovoltaics, wind, and solar), trauma is the primary occupational hazard during power production operations. Exposure to toxic brines, hydrogen sulfide and radon are also occupational and public health risks at geothermal plants (Hamilton, 2011).


Fuel Type and Carbon Emissions The two charts show the relationship between fuel type and carbon emissions for U.S. energy consumption in 2010. Source: U.S. Energy Information Administration
Fuel Type and Carbon Emissions. The two charts show the relationship between fuel type and carbon emissions for U.S. energy consumption in 2010. Source: U.S. Energy Information Administration

Fossil Fuel Power Benefits and Risks

Fossil fuel power production has allowed unprecedented industrial and population growth from a fairly low dollar cost energy source. Wilkinson et al. (2007) noted that the exploitation of fossil fuels is integral to modern living and has been a key element of the rapid technological, social and cultural changes during the past 250 years.  Their review paper noted that 2.4 billion of the world’s population, disadvantaged by a lack of access to clean energy, are exposed to high levels of indoor air pollutants from inefficient burning of biomass fuels.

Community health risks associated with fossil fuel power plants are unique, not because they are the only sources for certain pollutants, but because of the quantities of pollutants emitted. For instance, according to the EPA 2011 national emissions inventory data, fossil fuel power plants accounted for 69% of all anthropogenic emissions of sulfur dioxide (SO2) (EPA, 2014). The majority of power plant SO2 emissions are from coal (98%), further distinguishing them from natural gas-fired and oil–fired power plants (0.7%). Short-term exposure to SO2 has been associated with an array of adverse respiratory effects, including bronchoconstriction and increased asthma symptoms (EPA, 2014). Fossil fuel power plants emit approximately 51% of all anthropogenic mercury emissions, of which coal-fired plants account for 97% (EPA, 2014).  Mercury may remain in the atmosphere for long periods of time before depositing into the environment where it can bioaccumulate. Fossil fuel power plants also emit other hazardous heavy metal air pollutants, including arsenic (62%), nickel (28%) and chromium (22%) (EPA, 2014).

Risks to the natural environment from fossil fuel power plants include heavy metal discharges into water and ground water from coal pile runoff; leachate from coal ash landfills; discharges related to equipment maintenance and cleaning; cooling tower blowdown; discharges from wastewater treatment; and heavy metal air emissions that deposit into water and onto land surfaces. EPA surveys of groundwater near ash landfills and surface impoundments have demonstrated that arsenic may exceed human health thresholds by more than four orders of magnitude and poses the greatest risk for heavy metal discharges from coal plants (EPA, 1998). At oil-fired plants, arsenic, vanadium, and potentially nickel, are of greatest concern.

Power Plants often use billions of gallons of water for rivers, lakes and the ocean for use in cooling.
Power Plants often use billions of gallons of water from rivers, lakes and the ocean for use in cooling. Photo by Mark Shepherd


Another risk to the natural environment that does not involve a pollutant discharge is that of water withdrawals for cooling. To generate power, many power plants boil water to generate steam. The steam spins a turbine which generates electricity. After the steam passes through the turbine, it must be cooled to be recycled. To cool this water, power plants pull water from streams, rivers and estuaries for use in cooling towers or heat exchangers. A single power plant is able to pull hundreds of millions of gallons of water for use in cooling. In the United States, fossil fuel power plants account for 91% of all cooling water withdrawals (EPA, 2014). Large water withdrawals from lakes, rivers, estuaries and other water bodies may result in aquatic organisms being impinged on screens meant to filter debris. Small fish and eggs may be entrained, leading to a loss of early life stages needed to maintain healthy populations. A majority of power plants (71%) are also located within two miles of water bodies that are impaired due to excess nutrient loadings or other forms of pollution (EPA, 2014g). Thus, impingement and entrainment may exacerbate the loss of species and critical habitat from pollution.

The risks associated with fossil fuel power are not evenly distributed across fuel types or within fuel types. A study of non-climate change-related damages caused by air emissions from 406 coal-fired power plants estimated that 50% of the plants with the lowest damages together produced 25% of the net generation of electricity, while 10% of the plants with the highest damages also produced 25% of the net generation (National Research Council [NRC], 2010). Similarly, a review of 498 natural gas-fired facilities noted that there were major differences in pollution generation. Ten percent of the gas-fired plants accounted for 65% of the damage (NRC, 2010).


Greenhouse Gas Emissions from Fossil Fuel Power Plants

This natural gas-fired power plant along the south Texas coast has lower pollution emissions than similarly sized coal-fired plants.
This natural gas-fired power plant along the south Texas coast has lower pollution emissions than similarly sized coal-fired plants.
Photo by Mark Shepherd

Greenhouse gas (GHG) emissions from power plants have been identified as a long-term risk causing worldwide climate change (Schaeffer et al., 2015). The current and future impact from climate change depends upon a large number of factors, making risk estimation a complex and difficult undertaking. Haines et al. (2000) identified GHG risks to human health that include direct exposure to thermal and weather extremes, and indirect effects that include alterations in vector-borne infectious diseases, water quality and quantity, and changes in agricultural productivity. An example of vector-borne disease risk from climate change includes that of the St. Louis encephalitis virus. The virus, which can cause inflammation of the brain when transmitted to humans, depends on meteorological triggers for virus amplification between mosquitoes and wild birds (Day, 2001). Several researchers reported that climate change has caused an earlier onset of the spring pollen season in the Northern Hemisphere, potentially exacerbating asthma symptoms (D’Amato et al., 2002; Weber, 2002; Beggs, 2004). Other impacts from climate change include regional declines in fish populations (Brooks et al., 2002). Moore et al. (2008) identified potential impacts in marine and fresh water systems that include lower pH, changes to vertical mixing, precipitation and evaporation, and harmful algal blooms.

Forty percent of all greenhouse gases are emitted by fossil fuel power plants (75% of these are from coal-fired plants) (EPA, 2014). As of 2011, fossil fuel power plants in the United States that emit 25,000 tons or more of carbon dioxide equivalent (CO2e) greenhouse gases must report annual emissions to the EPA. The list of chemicals regulated under the program includes carbon dioxide, methane, nitrous oxide, and a number of fluorinated hydrocarbons. Fossil fuel power plants primarily emit carbon dioxide, with smaller quantities of methane and nitrous oxide. While carbon dioxide is the greenhouse gas emitted in large quantities, methane and nitrous oxide have larger global warming potentials (GWP). Methane has a 25 times larger GWP and nitrous oxide has a 298 times larger GWP than CO2.


Occupational Risks

Compared to other industries, occupational injury numbers and rates in the United States are generally low among power generating facilities. The Electric Power Research Institute (EPRI) collects and publishes information on the number of occupational injuries and illnesses reported by participating power facilities. EPRI reported that the most frequent types of injury (1995-2011) was sprains and strains (38.5%); cuts, lacerations and punctures (15.2%); and contusions and bruises (8.5%) (EPRI, 2013). The greatest occupational risks are associated with fossil fuel power plants. The United States Department of Labor (DOL) shows one fatality per year in 2012 and 2013 among fossil fuel electric power generating plants (DOL, 2014). In 2013, 82% of the approximately 2,200 recordable injuries within the power generation industry occurred at fossil fuel power plants. Nonfatal injury incident rates per 100 full-time employees at fossil fuel power plants was 1.4 in 2013, which interestingly is lower than hydroelectric power generation (2.3), but higher than nuclear power generation (0.2) (DOL, 2014). Illnesses such as respiratory conditions, poisonings from chemicals, and skin diseases are generally low at fossil fuel power plants. Hearing loss, however, represents the highest illness category among fossil fuel plants. In 2013, hearing loss incident rates per 10,000 full-time employees at fossil fuel plants was 20.1, or approximately 55% of all the reported illness incidents (DOL, 2014).

Exposure to coal dust at coal-fired power plants has not resulted in illness rates similar to those in coal mines (DOL, 2014). The reason is not completely understood. While coal ash (material remaining after coal combustion) contains many of the same mineral and metal constituents as coal dust, it does not appear to be as toxic (Borm, 1997).



To address these risks the EPA has proposed a number of regulations to protect the community and natural environment, particularly for coal-fired and oil-fired power plants. Many are the result of continuing efforts that began decades ago to further reduce pollutants associated with a number of potential health effects.



Beggs, P.J. (2004). Impacts of climate change on aeroallergens: past and future. Clinical and Experimental Allergy, 34, 1507-1513. doi:10.1111/j.1365-2222.2004.02061.x

Brooks, A. J., R. J. Schmitt and S. J. Holbrook. (2002). Declines in regional fish populations: have species responded similarly to environmental change? Marine and Freshwater Research, 53(2), 189-198. doi:10.1071/MF01153

D’Amato, G., Liccardi, G., D’Amato, M., Cazzola, M. (2002). Outdoor air pollution, climatic changes and allergic bronchial asthma. European Respiratory J., 20, 763-776. doi:10.1183/09031936.02.00401402

Electric Power Research Institute (EPRI). (2013). Occupational health and safety database 2012: annual data reporting years, 1995-2011. Retrieved from

Haines, A., McMichael, A.J., Epstein, P.R. (2000). Environment and health: 2. Global climate change and health. Canadian Medical Association J., 163(6), 729-734.

Moore, S.K., Trainer, V.L., Mantua, N.J., Parker, M.S., Laws, E.A., Backer, L.C., Fleming, L.E. (2008). Impacts of climate variability and future climate change on harmful algal blooms and human health. Environmental Health, 7, 1-12. doi:10.1186/1476-069X-7-S2-S4

Schaeffer, M., Gohar, L., Kriegler, E., Lowe, J., Riahi, K., Van Vuuren, D. (2015). Mid- and long-term climate projections for fragmented and delayed-action scenarios. Technological Forecasting and Social Change, 90, 257–268. doi:10.1016/j.techfore.2013.09.013.

United States Department of Labor. (2014). Industry injury and illness data. Retrieved from Bureau of Labor Statistics website:

United States Environmental Protection Agency. (2014). Cleaner Power Plants Mercury and Air Toxics Standards (MATS) for Power Plants US EPA. Retrieved from

United States Energy Information Agency. (2013). How many and what kind of power plants are there in the United States? FAQ U.S. Energy Information Administration (EIA). Retrieved from
United States Energy Information Agency. (2014). Monthly Energy Review – Energy Information Administration (DOE/EIA-0035(2014/10)). Retrieved from

Weber, R.W. (2002). Mother Nature strikes back: global warming, homeostasis, and implications for allergy. Annals of Allergy Asthma and Immunology, 88, 251-252. doi:10.1016/S1081-1206(10)62004-2