Radiation & DNA
When an alpha particle hits our DNA it can cause damage to a cell´s blueprint. Cells constantly replicate themselves, but with a broken blueprint the replication process can become cancerous.
According to particle physics, any form of radiation can behave as both a particle and as a wave depending on how you observe it. That is why an alpha particle is the same as alpha radiation.
All our cells contain DNA, which acts as an instruction manual or blueprint for cells on how to create copies of themselves.