What are the things that people can do to protect your environment from pollution?

Well, they can,

Decompose - Bury paper, cardboard, and food in the ground, so that it doesn't produce harmful methane gas in the atmosphere.

Carpool - This protects from to much CO2 in the air, which is why it gets hot in the summer.

Use solar, Hydro, or Wind energy to get electricity.

Overall, just pay attention to what you are doing. If it seems pollutional, don't do it.