Don’t confuse breath (a noun) and breathe (a verb).
Breath is pronounced /breθ/ and means ‘the air that goes in and out of your body through your nose or mouth’:
I could smell whisky on his breath.
Breathe is pronounced /briːð/ and means ‘to take air into your lungs through your nose or mouth and let it out again’:
✗ Without plants, we could scarcely breath.
✓ Without plants, we could scarcely breathe.
✗ These children have to breath contaminated air.
✓ These children have to breathe contaminated air.