See how concern about pollution led to the passing of major environmental laws in this video from the American Masters film, A Fierce Green Fire. While initially many technological innovations after World War II were welcomed, some of these new technologies had harmful side effects. In her book Silent Spring, Rachel Carson showed how some pesticides were threatening wildlife. After the first Earth Day in 1970, environmental laws like the Clean Air Act, Clean Water Act, and Endangered Species Act were signed or strengthened and the Environmental Protection Agency was created.