FILE - An estimated 7,000 persons jam a quadrangle at the Independence Mall in Philadelphia, during Earth Week activities celebrating the eve of Earth Day, April 22, 1970. (AP Photo)FILE - An estimated 7,000 persons jam a quadrangle at the Independence Mall in Philadelphia, during Earth Week activities celebrating the eve of Earth Day, April 22, 1970. (AP Photo)

Earth Day celebrates its 54th anniversary on Monday, April 22. On this date each year, millions of people around the world mark the importance of protecting the environment.

Worries about pollution and the environment began to increase in the 1960s. In 1962, American scientist Rachel Carson published her book “Silent Spring.” It warned of the use of a chemical called DDT. The chemical kills insects but also harms larger animals. The book became popular in the United States and other countries. As a result, more people became concerned about the environment.

Gaylord Nelson, a U.S. senator from the state of Wisconsin, had the idea that would become Earth Day. Nelson saw damage from a large oil spill in the ocean near the state of California in January of 1969. At the same time, people at some universities were holding events called “teach-ins” to call for action against the war in Vietnam.

Nelson’s idea was to hold a national “teach-in” on the environment. Along with environmental activists, Nelson worked to expand the idea beyond universities.

The activists wanted as many students as possible to take part. So, they chose a weekday between spring break and final exams. On April 22, 1970, the first Earth Day took place.

FILE - "Earth Day" demonstrators trying to dramatize environmental pollution conclude their rally at the Interior Department in Washington April 22, 1970, leaving spilled oil in their wake. The oil was used to protest pollution by off-shore oil drilling. (AP Photo).
FILE – “Earth Day” demonstrators trying to dramatize environmental pollution conclude their rally at the Interior Department in Washington April 22, 1970, leaving spilled oil in their wake. The oil was used to protest pollution by off-shore oil drilling. (AP Photo).

After the first Earth Day, the U.S. Congress approved more laws to protect the environment. In December of 1970 it added more rules to the Clean Air Act. And in 1972, it passed the Clean Water Act.

Many consider Earth Day to be the beginning of the modern environmental movement. In 2000, the Earth Day organization started placing more attention on the warming of the Earth’s atmosphere.

This year, the event is centering on the harm that plastics can bring to the environment. Activists are calling for the end of single-use plastics.

Earth Day is not an official holiday in the United States. But many groups use the day to put together volunteer events, such as cleanups of natural areas.

At the website EarthDay.org, you can see a list of events around the world or organize your own event.

I’m Andrew Smith.

Andrew Smith adapted this story based on reporting from The Associated Press.