This paper describes a distributed system for workers' safety enhancement, designed for operation in large working site and based on the LoRa network technology. The proposed system consists of a two-level network architecture. The first level consists of Body Area Networks (BAN) and Wireless Body Area Networks (WBAN) embedding specific and different wearable sensors and smart wearable devices which can gather signals related to the individual worker conditions. The information gathered by the sensors is managed and processed locally through devices belonging to the local body network itself (concentrators), in order to extract synthetic parameters. These latter are combined with information related to environmental monitoring such as presence of toxic gases and temperature, the fused information is finally transmitted with low rates through the LoRa network.