In his book “The Consumer’s Guide to Effective Environmental Choices,” Leon addresses questions environmentally conscious consumers face every day: Paper or plastic? Minivan or station wagon? Cloth diapers or disposables? Beef or chicken? Leon argues that because some decisions, such as the choice of a car, have a disproportionately large effect on the environment, there is little reason to feel guilt over the occasional paper cup tossed in the trash. At Bates, Leon will discuss how individuals can most effectively improve environmental quality through their purchasing and consumption and priority actions individuals can undertake in their personal lives to reduce environmental damage.

Leon is a former member of the Union of Concerned Scientists in Cambridge, Mass., where was deputy director of programs and oversaw the organization’s research, advocacy and educational outreach. He also co authored “A Small Price to Pay: U.S. Action to Curb Global Warming is Feasible and Affordable.”

Other Earth Day activities at Bates College include a “Mountain of Clothes” from 8 a.m. to 4 p.m. Participants will clean out their closets and bring unwanted clothing to help build a mountain of clothes on the Chase Hall terrace. Clothing will be donated to charity. Call Camille Parrish, environmental coordinator at Bates College, at 207-786-8319 for more information. A guided nature walk at Lewiston’s Thorncrag Bird Sanctuary will be held from 10 a.m. to noon. Participants are asked to meet at 9:45 a.m. outside Chase Hall for transportation to Thorncrag. Contact Camille Parrish at 207-786-8319 to register. A cleanup of Mount David will be held from 2 to 3:30 p.m. “Celebrating the Places We Call Home: Stories from Lewiston-Auburn,” stories and photographs of Lewiston-Auburn citizens as collected by Bates students in Environmental Studies 212 will be held from 3 to 7:30 p.m. in Chase Hall.