A dog's sense of smell is very different from a human's.
The inner surface of a dog's nose is lined with a thicker and more extensive olfactory epithelium compared to humans.
While humans have an olfactory epithelium that is about 7-10 cm², dogs have one that spans approximately 250-400 cm², making it 15 times larger.
This allows dogs to distinguish smells from distances up to 1 km or even more.
Humans tend to "listen" to smells, but dogs simply breathe them in.
They take 3-7 breaths in quick succession, gathering information within their nasal cavity.
This process concentrates the smell, helping the dog to identify it more accurately.