By: Susie Hairston

You’ve probably seen in the papers that the EPA is trying to overturn the endangerment finding, and maybe you know what that is and why it is important, and maybe you don’t, but now would be a really good time to gain a basic understanding of it.

What is the endangerment finding? In a nutshell, the 2009 Endangerment Finding is the reason the EPA not only is able to, but must, regulate six greenhouse gases (GHGs) emitted from stationary (industrial facilities and power plants, for example) and mobile sources (such as cars) under the Clean Air Act. Without the endangerment finding, these GHGs would not be regulated. If this happens, factories, power plants and cars and trucks will have no limits on the amount of greenhouse gases they can pour into the atmosphere, thus speeding up climate change and worsening its impacts on human health.

How does climate change impact human health? Among other problems, as the planet warms, increases in wildfires, droughts, water-insecurity, flooding, hurricane intensity, and vector-borne diseases are threats to human health that are already taking their toll on us and will only get worse.

A little about the Clean Air Act:

The Clean Air Act of 1970 authorized the development of comprehensive federal and state regulations to limit emissions from both stationary (industrial) sources and mobile sources (such as cars) and established 4 major regulatory programs: Ambient Air Quality Standards, State Implementation Plans (SIPs), New Source Performance Standards (NSPS), and National Emission Standards for Hazardous Air Pollutants (NESHAPs). At the same time the EPA was established to implement these regulations and programs.

The Clean Air Act did many things to address air pollution and protect human health including establishing emissions standards for mobile sources, like cars and requiring new stationary sources of pollution (power plants and factories, for example) to use the best available technology to minimize pollution.The Act had provisions to address hazardous or toxic air pollutants such as carcinogens, neurotoxins, and endocrine disruptors that pose a threat to human health. It also included the authority to address pollutants that were discovered/developed later or were not recognized as harmful to human health at the time of the passage of the Clean Air Act, but emerge as pollutants over time, such as greenhouse gases that cause climate change.

These last two, the ability to regulate emissions determined to be harmful to human health and welfare and the ability to start regulating substances found to be harmful to health in the years after the Clean Air Act was passed though these pollutants were not originally designated as such, in conjunction with the 2009 Endangerment finding, formed the legal basis for adding six greenhouse gases to the list of air pollutants that must be regulated under the Clean Air Act.

How did the EPA determine that six greenhouse gases (carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride) were a danger to human health and welfare? 

After the Supreme Court, in 2007, determined that greenhouse gases were pollutants as defined by the Clean Air Act, the EPA, now mandated to act, examined scientific evidence, including evidence from NASA, NOAA, the National Academies, and the EPA’s own studies, as well as thousands of peer reviewed studies that showed that the rise in greenhouse gases in the atmosphere were leading to climate change, which in turn was threatening public health and welfare. The EPA linked these GHGs to increased heat waves, ground-level ozone (smog), and more severe extreme weather events, which all led to harm to human health.

Then the  EPA proposed its “endangerment” and “cause or contribute” findings for public review and comment. The 60-day public comment period, which ended in June 2009, generated over 380,000 comments. 

The EPA, after careful consideration of the evidence and the public comments, determined that GHGs were harmful to human health and issued the endangerment finding in December 2009. 

The EPA, as required under the Clean Air Act,  then began to mandate that stationary sources of GHGs use the latest technology to limit their emissions and set emissions standards for new mobile sources ( cars, etc.).