Can emphysema affect small children?

Yes. 3% of babies in the neonatal intensive care unit can have interstitial pulmonary emphysema. There is a genetic condition that causes low levels of an enzyme that protects the lungs, and these patients can get emphysema even without smoking, but it does not affect small children. (it might be apparent in their 30's or 40's). Thanks @yayayarndiva.
Yes. In premature infant due to higher risk for aspiration, infection, and being on ventilator. Also in children congenital problem such as alpha1-antitrypsin (aat) deficiency may cause that.