A certified health physicist is someone who knows a lot about radiation, which is a kind of energy that can be harmful to our bodies if we're exposed to too much of it. They help keep people safe from radiation by making sure that places where radiation is used, like hospitals or nuclear power plants, are following all of the rules to keep workers and the environment safe.
It's kind of like when you're playing with your toys, and your mom or dad tells you that you can't touch something because it's dangerous. They want to keep you safe, just like a health physicist wants to keep people safe from radiation.
To become a certified health physicist, you have to go to school and learn a lot about physics, which is how we understand how things in the world work.
Then you have to work for a while, building experience and learning from other health physicists. Finally, you have to take a test to show that you know enough about radiation and how to keep people safe from it to become certified.
In the end, a certified health physicist is someone we can all rely on to help make sure that we're safe from the harmful effects of radiation.