Environmental noise is increasing year after year and, besides annoyance, it causes harmful health effects on people according to last 2018 WHO report. The Environmental Noise Directive 2002/49/EC (END) is the main instrument of the European Union to identify and combat noise pollution, followed by the CNOSSOS-EU methodological framework. In order to apply the END legislation, the EU Member States have to publish noise maps and action plans every five years. The use of Wireless Acoustic Sensor Networks (WASNs) changes the paradigm that addresses the END regulatory requirements as they enable the dynamic ubiquitous measurement of environmental noise pollution. Following the END, the DYNAMAP project develops a WASN-based low-cost noise mapping system to monitor in real-time the impact of road infrastructures in two pilot areas: Milan and Rome. To avoid biasing the noise maps with noise levels unrelated to traffic noise, an Anomalous Noise Event Detector (ANED) is included to remove them from the corresponding LAeq. The paper reflects the adaptation of the ANED algorithm to the WASN of the suburban area of Rome, which requires a specific analysis of the particularities of the suburban audio database, as well as future challenges and research on the generalization of the WASN.