http://www.psni.police.uk/index/advice-and-legislation/firearms/advice_firearms_know_the_law.htm
Airguns not Requiring a Firearm Certificate
In Northern Ireland airguns and CO2 guns having a discharge kinetic energy in excess of one (1) Joule (0.737 ft lbs) require to be held on a firearm certificate. For airguns below that limit the following restrictions are in place.
Under Paragraph 9 of Schedule 1 of the Firearms (NI) Order 2004, persons under the age of 18 cannot possess such firearms, unless they have attained the age of 14 years or are under the direct supervision of a perso