A detailed modelling assessment must be carried out where the background value of ammonia is already at or exceeding the levels which cause detriment to species in sensitive sites.
Rhaid cynnal asesiad modelu manwl lle mae gwerth cefndir amonia eisoes ar y lefelau neu'n uwch na'r lefelau sy'n achosi niwed i rywogaethau ar safleoedd sensitif.