People: This is a study based on research using people. International scientists say it can take more than 25 years for the heart health of heavy smokers to return to normal after they quit, but a ...

total_bill tip sex smoker day time size 0 16.99 1.01 Female No Sun Dinner 2 1 10.34 1.66 Male No Sun Dinner 3 2 21.01 3.50 Male No Sun Dinner 3 3 23.68 3.31 Male No Sun Dinner 2 4 24.59 3.61 Female No ...