I think you could use either word and be understood. I would personally choose decompose. I mostly associate decay with organic material or radioactive material.
Student or Learner
Which is the right word to say:
1. Plastic bags decompose/decay very slowly and are harmful to the environment.
2. It takes years for plastic to decay/decompose.
Which sentence is correct?
I know I can use decompose and decay while talking about organic objects such as body, wood, plants. And what about plastic bags that we can have from shopping centers? Do they decompose or decay?
I'm not a teacher yet, but I am studying a Bachelor of Education with an English Literature major at Charles Sturt University, in NSW, Australia.