This paper deals with the design of a lightweight sensor scheduling algorithm in clustered wireless sensor networks (WSNs) for environmental observation. The aim is that of achieving energy savings and a fair distribution of the sensing task among WSN nodes, while ensuring that critical network tasks, such as data fusion, are not impaired. The proposed scheduling policy takes into account feedback on nodes' health status and the quality of the information provided by the nodes to be scheduled. As a result, dynamically variable schedules are produced, adapted to the current status of the WSN. Simulation results are presented to highlight the relevant features of the algorithm.