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In 1970, the National Library of Medicine featured an exhibition, The Darkening Day, that illustrated the detrimental health effects of environmental pollutants. In that same year, millions of Americans took to the streets in observance of the first Earth Day on April 22.

Fifty years later, this exhibition highlights examples of the research, programs and policies, public messaging, and action taken by the U.S. Department of Health, Education and Welfare and federal scientists from the Public Health Service (PHS) in the years leading up to The Darkening Day.

Rachel Carson

In the Wake of Silent Spring

Rachel Carson, marine biologist and writer, researched pesticides in the late 1950s. Carson’s findings led to her book Silent Spring, published in 1962, which warned of the detrimental effects of pesticides on the environment.

Today, Silent Spring is considered one of the major catalysts for the modern environmental movement.

An open book.

Black and white portrait of a white woman.
A typed page.

“The contamination of the environment with harmful substances is one of the major problems of modern life…. Now we are receiving sharp reminders that our heedless and destructive acts enter into the vast cycles of the earth and in time return to bring hazard to ourselves.”

-- Rachel Carson, Statement before Congress, 1963

Air Pollution

A Rising Public Health Crisis

In 1948, the PHS began studying the health effects of air pollution after 20 citizens died and many became ill from smog in Donora, Pennsylvania.

A typed page.
A book cover.

An open book.

By 1955, Congress passed Public Law 159 giving the PHS funding to establish dedicated programs for the study and control of air pollution.

New Workforce

The Public Health Service

Rising research on pollution inspired the PHS to establish new environmental health research, regulation, and community engagement programs. This required staff with diverse expertise in many scientific fields such as toxicology, biology, public health, and medicine.

A typed letter.
A typed letter.
A page in a book.


Uranium in the Four Corners: A Case Study

Uranium, a naturally occurring radioactive substance, was heavily mined in the latter half of the 20th century in the Four Corners region of the Western United States. By the 1980s, many uranium mines were abandoned after studies found uranium to cause health problems.

A green and orange map of the Colorado Plateau, United States.
A white man standing leans down while taking blood from a seated Native American man in a hard hat.

A book cover.
A typed letter.

Navajo families living near inactive mines remain at risk, long after the uranium industry left the Four Corners region.

Public Access

Sharing Information

The PHS reprinted and distributed informative pollution-related content from journalists to TV and film documentarians, and even cartoonists.

By 1962, PHS publications and other media were made freely available through depository libraries of the Government Printing Office (GPO). Expanding public access to PHS publications at this time made diverse information on pollution available to all.

A book cover with an image of a foggy urban street and another image of a crowd seen from a bird's-eye view.
A book cover with black and white film stills.
A book cover with a bird's-eye view of a city skyline surrounded by clouds.

Mobilizing People

Government Pamphlets

Many government and government-funded pamphlets on pollution encouraged citizens to help create a healthier environment.

A page from a book with a graph and illustrations of an industrial landscape and the map of the United States.
A book cover with an illustration of a city skyline partially covered in smog.

Some used statistics, data visualizations, and case studies as calls to action. Some gave tips on how to raise awareness and foster change. Each emphasized the need for collaboration between communities and all levels of government.

A pamphlet cover with a blue image of a stream.
A pamphlet cover with an illustration of a man climbing steep steps while covered by smog below.


The National Library of Medicine produced this exhibition.

Guest curator: Tannaz Motevalli
Exhibition Designer: HealyKohler Design