Source Core Rulebook

A torch burns for 1 hour, shedding normal light in a 20-foot radius and increasing the light level by one step for an additional 20 feet beyond that area (darkness becomes dim light and dim light becomes normal light). A torch does not increase the light level in normal light or bright light. If a torch is used in combat, treat it as a one-handed improvised weapon that deals bludgeoning damage equal to that of a gauntlet of its size, plus 1 point of fire damage.