yekke2: My response got blocked, but I will summarize.
If the Chazon Ish knew how to do brain surgery from learning Toirah, Kal V’Choimer the P’nei Yehoshua knew what smoking would do to the lungs from his vast knowledge of Toirah! And still, the P’nei Yehoshua said smoking is healthy. Either “Nishtanu HaTeva” (which I have never seen in an anti-smoking P’sak) , or the studies were not done on Yidden, who react physically differently than Eino Yehudim (as per Chazal).
(Poe’s)