Later this month, Pokémon Go players will get rewards for picking up garbage. Today, developer Niantic revealed a series of events occurring on April 22nd to celebrate Earth Day. Since the game is so good at getting people to gather in public spaces, the developer is partnering with local NGOs across the world to encourage that behavior, and then get players to team up to clean those spaces. And the more people who show up and help, the bigger the in-game rewards will be.

Here are the details from Niantic:

All trainers will receive access to a special avatar item to celebrate Earth Day and those who work together to participate in the cleanups around the world will unlock unique in-game rewards for the entire world. If 1,500 trainers attend the events around the world, 2x catch stardust for ground, water, and grass-type pokémon will be unlocked for 48 hours. If more than 3,000 trainers participate in the clean up events, 3x catch stardust for ground, water, and grass-type pokémon for 48 hours will be unlocked for trainers around the world.

Previous live events for the game haven’t gone especially smoothly, but it’s good to see Niantic attempt to use Pokémon Go for a good cause. “Earth Day is an incredible movement and opportunity to team up with friends and neighbors to focus on making the world and our own communities healthy and sustainable,” Niantic CEO John Hanke said in a statement. There will be a total of 37 events later this month across 12 countries — you can find the full list here. The news follows a major update for the game last week, which added new story missions and daily quests.