The actor who once portrayed the Marlboro Man cowboy in ads promoting cigarettes in the 1970s has died of causes related to smoking. The 72-year-old passed away from “respiratory failure due to chronic obstructive pulmonary disease (COPD),” a condition caused by his years of tobacco use. Though Eric Lawson rose to fame as the rugged, Old West Marlboro Man, he later became an anti-smoking advocate, and famously parodied his own work as the iconic cigarette spokesman to warn others about the dangers of the habit. Larson admitted that he didn’t stop smoking until he was diagnosed with COPD. His wife told the AP, “He knew the cigarettes had a hold on him. He knew, yet he still couldn’t stop.” He is the third actor to portray the Marlboro Man to die of a smoking-related disease …