JUYONGGUAN, China – The smog that has lingered over these Olympics both literally and figuratively had a chance to have its first affect on athletes yesterday.

The men’s cycling road race was the first endurance event of these Games, a 152.5-mile ride from the city of Beijing into the hills under the shadow of the Great Wall.

“I think the heat is what gets to you,” said American David Zabriskie, who did not finish. “If the smog becomes an issue, it will probably become an after effect when you’re home.”

The riders admitted they were a bit taken aback by the look of the sky here. It is the color of mop bucket water and is thick with humidity.

“Some people say it’s haze and humidity,” Zabriskie said. “I guess until you actually had a particulate monitor you really wouldn’t know.”