This is a polygon dataset of the strategic noise mapping of airports, in the form of noise contours for the Lnight (night) period for Dublin and Cork agglomerations airports. The dB value represents the average decibel value during the Lnight time. Any direct comparison of the Round 3 versus Round 2 results should be carefully considered, as changes to the model input datasets used between these rounds may be significant. This may especially apply to the terrain model used, while there may be improved building height data, & improved traffic flow data with fewer assumed flows. There may also be some revisions to the actual road network modelled in Round 3. The noise maps are the product of assimilating a collection of digital datasets, and over the last 10 years there has been significant improvements to the quality of the digital datasets describing the natural and built environment in Ireland. This has led to the strategic noise models giving much more reliable noise results with much less tendency to over predict the impact.