what is the largest most celebrated environmental event worldwide
Earth Day Flag created by John McConnell. Earth Day is an annual event, celebrated on April 22, on which day events worldwide are held to demonstrate support for environmental protection.t now is observed in 192 countries, and coordinated by the nonprofit Earth Day Network, chaired by the first Earth Day 1970 organizer Denis Hayes, according to whom Earth Day is now the largest secular holiday in the world, celebrated by more than a billion people every year..