They are white pimples that occur mostly on the upper cheeks, nose and chin. The best way to
prevent milia is to
avoid treating your skin
with excessively harsh chemicals and to
limit sun exposure.Also use good quality cosmetics and exfoliate your skin regularly.If still the symptoms persist then chemical peeling or laser removal can be done.Other treatment options include electrocautery and cryotherapy.
Hope it helps.Take care and pls do keep us posted if you have any additional queries.