Commuters were given free chocolate bars at Metro stations near the nation's Capitol.
Metro and the American Public Transportation Association teamed up to give out the goodies for being good.
Transit agency officials say the chocolate was a reward for saving 20 pounds of carbon emissions by riding public transportation on Earth Day.
Officials add that if just one person from each household switches from driving to public transit, the family's carbon footprint can be reduced by 10 percent.
