SPANISH FORK — Police say dense smog was the main contributing factor in a fatal traffic accident on U.S. 6 Thursday.

Nathan Hales, 48, of Spanish Fork, attempted to make a left turn at the intersection of 2550 East and U.S. 6 about 8:15 a.m., when he was struck by a semitrailer truck hauling a flatbed loaded with steel that ran a red light, according to Spanish Fork police.

Hales, who was declared dead at the scene, is the first cousin of Spanish Fork Police Chief Steven Adams. He is survived by his wife and five children.

The driver of the semitruck, a 59-year-old Orem man, told investigators that he slowed down as he approached the intersection due to the dense visibility, but he entered it sooner than he was anticipating.

Police estimate visibility was about 100 feet at the time of the accident.

The Utah Highway Patrol is investigating the crash due to the victim's relation to the police department. Officials had not determined Thursday whether charges would be filed against the truck driver.