Smoking on Tisha B'Av

Hello and blessings, 

According to Yechave Da'at part 5, siman 39, in summary: According to the basic law, it is permissible to smoke cigarettes on all public fasts, even on Tisha B'Av. However, it is advisable to be strict on Tisha B'Av specifically and refrain from smoking for pleasure. Especially one should be stringent during the reading of Eicha and lamentations in the synagogue. However, if there is some necessity, such as for someone who is very accustomed to smoking and experiences great discomfort without it, it is permissible for them to smoke in private on Tisha B'Av. 

Blessings, Binyamin Shmu'eli