An airbrick is a special type of brick that contains holes to allow the circulation of 'fresh' outside air beneath suspended floors and within cavity walls to prevent moisture building up as a result of cold or damp air 'sitting' in voids or empty spaces.

Can air bricks cause damp?

Instead the moisture builds up in the fabric of the wall and you have Interstitial Condensation that can only move back into the room and cause the plaster to become damp.

Will an air brick stop Mould?

If air lingers and stagnates it can lead to perfect conditions for black spot mould to form. Cleaning air bricks with a bottle brush once a year will greatly improve sub-floor ventilation and reduce the possibility of wood rotting fungal decay like dry rot.