Who Knew? The Implications of One Environmental Policy for Mental Health

November 22, 2019

The Clean Air Act (CAA) turned 55 years old last year. Most millennials and Gen Xers have had little idea what this legislation has meant for us, even though it may have given us each almost a year of productive life.

The Clean Air Act (CAA) turned 55 years old last year. Like me, most millennials and Gen Xers have had little idea what this legislation has meant for us, even though it may have given us each almost a year of productive life. Passed on December 17, 1963, and amended in 1970 and 1990, CAA was a milestone statute-the first federal law regulating air pollutants and demanding reductions in particulate matter, photochemical oxidants like ozone, carbon monoxide, sulfur oxides, nitrogen oxides, and lead. Over the last five decades, lead in the air has dropped 99%, nitrogen dioxide has dropped more than 60%, sulfur dioxide has dropped more than 90%, and ozone has dropped more than 30%.1 Even in the 28 years that I have been alive, the PM2.5 particulate air pollution that doubles our risk for dementia and causes developmental disorders has decreased 40% from previous levels.

I was not alive in the 1950s when the skies of New York City and London were yellow with smog that burned the eyes or when the headlines blasted the bad news of deaths in the Donora disaster in Pennsylvania in 1948.2 Yet, the cleaner air in the US that was motivated by those environmental disasters has probably had direct impacts on my mental health as well as that of everyone I know. Since the CAA 1970 Amendment that required lower emissions of lead, children’s blood lead levels in the US have continuously declined. Levels of lead found in human blood decreased more than 80% from 1976 to 1999 in American children aged one to five years, from 17.1 μg/dL to 2.0 μg/dL on average.3

Toxic accumulation of lead results in long-term neurodevelopmental and behavioral problems, including decreases in IQ scores, developmental delays, learning disabilities, antisocial behavior, and reduced educational attainment. Blood lead levels above 10 μg/dL in children, which were much more prevalent before CAA, have been reliably associated with cognitive impairment and behavioral problems such as attention deficit hyperactivity disorder. The impact of CAA on reducing lead emissions can be estimated to have prevented 10.4 million lost IQ points in children from 1970 to 1990. That’s about 15 million IQ points in my lifetime-about 0.14 IQ points for every child born since I was born.

During the same time frame, Americans worked 17 million more days than they would have if they had been sick from bad air. That may represent upwards of 200 productive days for me personally, and I may have also saved myself a trip or two to the Emergency Department for asthma exacerbations that I did not have.

Despite the great and continuing successes of CAA, however, there is reason for concern. In recent years, the greenhouse gas emissions (GHGs) that form much of the air pollution and are the main driver of climate change have begun to rise again, after five decades of steady decrease. In 2018, America’s carbon dioxide emissions rose by 3.4%, the biggest increase in 8 years, as Trump began to roll back EPA protections put in place by Obama to curb this trend.4

Ozone is on the rise. Four in ten Americans still live in places with unhealthy air despite study after study reinforcing that air pollution is doubling the incidence of autism, dementia, and other neuropsychiatric disorders.5 In fact, in late August 2019, the Trump Administration proposed a roll back on the regulation of methane, a GHG that has been shown to be 25 times more powerful than carbon dioxide in trapping heat in the atmosphere.

Air pollution traps heat and raises global temperatures and worsens extreme weather. These conditions disrupt the climate and are leading to a growing number of mental health symptoms and crises. Growing evidence has demonstrated the impact of rising temperature on suicidality. Helama and colleagues6 reported a positive correlation between temperatures and suicide rates in Finland using historical records from 1751 to 1990, when a national suicide prevention program was put into place.

A 2016 study of 29 European countries over a 13-year period showed that climatic variables were consistently a better predictor of suicide than socioeconomic factors.7 A more recent study found that as temperatures climbed over the course of decades in the US and Mexico, suicide rates also increased by 0.7% and 2.1%, respectively, for every 1°C increase in monthly average temperature.8 This study estimated that if temperatures continue to go up, climate change will cause a total of 21,770 excess suicides by 2050 in the US and Mexico!

I learned all this while working on a chapter for a forthcoming book to be published by American Psychiatric Association Publishing with help from my chapter editor Elizabeth Haase, MD, and lead editor Michael T. Compton, MD, MPH. It has changed me. I now understand how much difference one good law can make, and I plan to do my part in psychiatric advocacy to make sure we have many such supports for our mental health working for us in our government.


Dr Ku is a Psychiatry Resident, Emory University School of Medicine, Atlanta, GA. He reports no conflicts of interest concerning the subject matter of this article.


1. US Environmental Protection Agency. Air Quality: National Summary. 2016. https://www.epa.gov/air-trends/air-quality-national-summary. Accessed October 11, 2019.

2. Bachmann J, Calkins D, Oge M. Cleaning the Air We Breathe: A Half Century of Progress; 2017. https://www.epaalumni.org/hcp/air.pdf. Accessed October 11, 2019.

3. Grosse SD, Matte TD, Schwartz J, Jackson RJ. Economic gains resulting from the reduction in children’s exposure to lead in the United States. Environ Health Persp. 2002;110:563-569.

4. BBC News. (2018). Trump Rolls Back Decades of Clean Water Act Protections. https://www.bbc.com/news/world-us-canada-46526776. Accessed October 11, 2019.

5. Rascoe A. FACT CHECK: Trump’s Claims About “Record Clean” U.S. Air? NPR. 2018. https://www.npr.org/2018/11/28/671521901/fact-check-trumps-claims-about-record-clean-u-s-air. Accessed October 11, 2019.

6. Helama S, Holopainen J, Partonen T. Temperature-associated suicide mortality: contrasting roles of climatic warming and the suicide prevention program in Finland. Environ Health Prevent Med. 2013;18:349-355.

7. Fountoulakis KN, Chatzikosta I, Pastiadis K, et al. Relationship of suicide rates with climate and economic variables in Europe during 2000-2012. Ann Gen Psychiatry. 2016;15:19.

8. Burke M, González F, Baylis P, et al. Higher temperatures increase suicide rates in the United States and Mexico. Nature Climate Change. 2018;8:723-729.

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