The relative risk of smoking for migrants compared to the US-born group stratified by age at migration to the US by country of origin1.

1Country of origin is country of birth, except for second generation migrants where it is the country of birth of the parents.22nd Generation: those born in the US whose parents are both foreign-born.3Variance between all available categories.4No smokers in this group.*Significant (p≤0.05).**Other Africa: Ghana, Kenya and South Africa.