[Belegorn]

The enviroment probably did play a role in the diminishment of lifespans since it seemed to be the nature of Middle Earth with fading. In Aragorn's line unless they were killed his forebears were living to 150+ years. His Grandfather and father were both slain, but prior to them, going backwards, the Cheiftains ages were, 155, 155, 156, 156, 157, 157, 158, 159, et cetera. His father was killed with a poison missle to the eye, I believe, at 60 and his grandfather died at 110 by trolls in the mountains. If Denethor was like the nearest of kin to Aragorn I would think that Faramir was even moreso like him in behavior which is why he and Aragorn were pretty long-lived imo since we can see how the behavior of the Faithful and King's Men in Numenor effected their lifespans. The lifespan of the average man was 70 years and the average Numenorean had a lifespan 3 times that, which would be 210 [70 X 3] which was what Aragorn was when he died.