Fire rescue operation is one of the most critical public safety activities where the firefighters put their lives to direct risk in order to extinguish the fire and help save other humans. For the success of fire rescue operation it is very important that the incident commander and the firefighters in the fire field are completely aware of their surroundings. Situation awareness can be achieved by a firefighter monitoring system consisting of sensors implanted in the firefighter's uniform. Like any other sensor application, the sensor nodes should remain alive till the end of rescue operation and should send regular updates to the incident commander. In this paper we propose an energy aware sensing and transmission (EAST) scheme for the firefighter monitoring system. The proposed scheme computes the on-off scheduling scheme for the sensor nodes depending upon the expected maximum operation time, the residual energy and update period of the sensor nodes. Simulations are performed and comparisons are made in MATLAB. It is shown that the EAST scheme achieves the energy efficiency within the update period constraints when compared to other schemes.