Sunshine-cured tobacco, Bastam, Iran Curing and subsequent growing old let for the slow oxidation and degradation of carotenoids in tobacco leaf. This makes sure compounds during the tobacco leaves and provides a sweet hay, tea, rose oil, or fruity aromatic flavor that contributes to the "smoothness" of your smoke. https://broadfar.com/non-combusted-cigarettes-a-safer-alternative-or-just-a-myth/