Radiation - The Unwanted Guest

How do I get a radon test kit?  Are they free?
https://www.epa.gov/radon/how-do-i-get-radon-test-kit-are-they-free

Radiation Terms and Units
https://www.epa.gov/radiation/radiation-terms-and-units

Radioactive Decay
https://www.epa.gov/radiation/radioactive-decay

The Difference Between Radiation And Radioactivity
https://theconversation.com/explainer-the-difference-between-radiation-and-radioactivity-20014

Geiger-2 Dosimeter / Geiger Counter / Radiation Detector
https://www.mirasafety.com/products/geiger-counter-radiation-detector-dosimeter