The road traffic noise levels at the A12 motorway near Voorburg were lower in 2008 than in 2007. This decrease results from the repaving of the road surface with a double porous asphalt layer (DLPA) in September 2007. The reduction in noise level realized at this time was sustained in 2008. The noise level at the A10 motorway near Amsterdam, however, was found to have increased slightly over the course of 2008. Measurements taken in 2006 indicated that most of the noise reduction effect of the porous asphalt layer installed in 2001 had disappeared. This decreased capacity to reduce noise is likely due to silting up of the pores and texture wear due to intensive traffic. These are the main results of Noise monitor 2008. The monitoring programme was initiated in 1999 with the aim of monitoring trends in environmental noise levels due to road and rail traffic. Noise measurements in 2008 were carried out at locations along the A2 (Breukelen), A10-west (Amsterdam), A12 (Voorburg) and N256 (Noord-Beveland) motorways. Measurement results provided by ProRail at Esch and Willemsdorp were used for the analysis of railway noise. Results of sample measurements of urban traffic carried out by the RIVM in Utrecht in 2009 are also presented. The noise emission levels measured for road traffic at the monitoring sites with standard pavement (DAC) were found to be a few decibels higher than the reference value of the Dutch computation method, while those at the monitoring sites for railway noise were fairly consistent with the predicted value. The computation methods are provided by the Dutch Ministry of Housing, Spatial Planning and the Environment to calculate noise due to road and railway traffic.