The data collected from IoT devices on various emissions or pollution can have significant economic value for stakeholders. This makes it prone to abuse or tampering and brings forward the need to integrate IoT with a DLT to collect, store, and protect the IoT data. However, the DLT brings additional overhead to the frugal IoT connectivity and symmetrizes the IoT traffic, thus changing the usual assumption that IoT is uplink-oriented. We have implemented a platform that integrates DLTs with a monitoring system based on NB-IoT. We evaluate the performance and discuss the trade-offs in two use cases: data authorization and real-time monitoring.