Brad Pitt's (search) voice is usually identified with movies such as "Troy," "Ocean's Eleven" and "Twelve Monkeys" — not a six-hour documentary on global health.

Starting Tuesday night on PBS (search) and ending Thursday (check local listings), Pitt will narrate six hour-long episodes of "RX for Survival: A Global Health Challenge," (search) which follows health care workers and researchers struggling to contain disease among the world's poor.

"I've been involved with the issue of poverty — I've been studying it for about a year and half now," Pitt told The Associated Press in a phone interview Monday from Calgary, Alberta. "I think one of the major causes of that is health, global health."

Pitt has made several trips to Africa in the past two years, including one in July to Ethiopia, where his "Mr. & Mrs. Smith" co-star Angelina Jolie adopted her daughter, Zahara.

While tabloid coverage of Pitt and Jolie has been extensive, the 41-year-old actor told Diane Sawyer on ABC's "Primetime Live" in June that he wanted to redirect some of that attention to poverty in Africa.

"I think it could be one of the major issues of the century," he told the AP. "There are two things at stake here: one is human interest and the other is self-interest. We're finding out that there's no safe haven from infectious diseases. It's a plane flight away."

"The human interest is enough — the fact that millions are dying from preventable, curable diseases," Pitt said. "But if the human interest isn't enough, then wisdom will tell you that self-preservation is."

He mentioned the Avian bird flu as an example, and said he wondered if AIDS might not have "jumped the pond" if Africa had a proper health infrastructure.

What led Pitt to this interest in poverty?

"I don't know," he said. "To me personally, it goes back to the will to understand and that's what we're lacking most. So I want to educate myself as much as I can to understand the situation, to understand the solutions."

"I've had the luxury of travel and in the luxury of travel, I've seen the detriments of poverty and I've gone on to see how easy the cures can be — cures that cost cents to the richest nation in the world."