What factor significantly increases the risk of drug-related crashes?

Driving under the influence of a differentiating substance significantly increases the risk of drug-related crashes because it impairs the driver’s ability to operate the vehicle safely. This can affect various cognitive and motor skills such as judgment, attention, reaction time, and coordination. When a driver is under the influence, they may not respond to traffic signals or hazards appropriately, leading to an increased likelihood of accidents. Impairment from drugs can also result in diminished perception of speed and distance, making it harder for a driver to navigate safely through different driving conditions.

Other conditions such as driving without a valid license, low visibility, and high traffic areas can contribute to the risk of accidents, but drug impairment is a direct cause of reduced driving performance. Thus, it stands out as a critical factor in assessing crash risk.