The answer is: 0.08%
When our blood alcohol level reaches 0.05% , we will experience minor impairment in our memory and judgement. Compared to normal condition, this will significantly rises our risk of accidents.
After our blood alcohol level reaches 0.08% , speech, vision, reaction time, and hearing Impairment would be added to the equation. Which makes the likelihood rises rapidly compared to 0 .05% BAC.