how is smell measured?how does it travel?

Question

why is the smell of a flower within it while the smell of perfumes spread fast?

Answer 1

Smell is not measured. The chemicals (molecules) that are detected can be measured and identified using instruments like gas chromatographs.

Flowers and many natural smells are composed of large complex molecules which do not travel very far in the air. Most artificial smells are made from small simple molecules which have a high vapor pressure and travels great distances.

Check out the references below:

Answer 2

You would think that the smell could be measured in terms of the concentration of particles in the air. the speed of smell is related to the circulation of the air.

Its not standard to do so but certainly a chemist or a physicist could find a way to do it.

They likely do but dont label it smell.