In the United States and much of Europe, research suggests that regular lighting up typically begins between 15 and 16 years old. In the US, 15.3 was the average age when adult smokers reported smoking initiation, according to a 2014 surgeon general's report. [...] Across European countries, the rates of smoking initiation peaked at 16 among boys and 15 among girls in the 2000s, according to a study published in the journal PLOS One on Wednesday.