A hint of air
After several more hours of traveling though the passages he again found himself at an intersection and decided to use his last match. Knowing it was his last, he lit it and then used it to light the match box on fire. He was amazed how bright it was, for the first time in days he was able to see more than six or so feet. He could clearly see two different directions to travel, he had to decide in the flickering light of the burning matchbox. Hey, wait, the matchbox was flickering, none of the other matches he lit ever flickered, it seem to be flickering towards the right, there was a slight draft, not strong enough for him to feel but strong enough to make the burning matchbox flicker, he had new hope as he proceeded down the right passage as the last of the burning matchbox flickered out.