Cleveland R H
Radiology. 1979 Oct;133(1):89-93. doi: 10.1148/133.1.89.
The bronchial angles in children from birth to age 18 years were measured. Symmetry of angles was found to age 15 years. After that age, an aortic indentation was generally noted on the trachea with an increased left bronchial angle. Hence, the relatively equal incidence of right- and left-sided aspiration of foreign bodies in smaller children as opposed to adults.