"Let's work together and start an antipollution campaign, let's click pictures & post them on social media! You'll see how fast we will gain popularity! " "Bro ! Pollution isn't there outside, it's in your mind, Cure it first !" OPEN TO ALL For the participants of One World, One Voice : This is the first prompt of Day 4. ☺ The theme of World Environment Day 2020 is “Celebrate Biodiversity”. With 1 million species facing extinction, there has never been a more important time to focus on biodiversity.