The harsh construction environment requires unusually robust sensing and actuation technology to make real-time pro-active safety alerts a reality. We have developed a batteryless, wireless sensing and actuation device as an option to advance pro-active safety in construction. By employing electromagnetic energy harvesting and eliminating the need for a battery, our device will function in harsh environments for many years without requiring service or maintenance. In addition to the sensing capabilities normally associated with passive RFID tags, which also employ electromagnetic energy harvesting, we have also included a piezoelectric speaker to generate and transmit audio warning signals to warn workers of dangerous situations. Ultimately, the device will be affixed to a safety hard hat, dubbed a "SmartHat" which will audibly alert a worker if an RFID reader-equipped hazard is nearby. We have developed a custom antenna design for plastic hard hats that exhibits good omni-directional performance. We will describe our "SmartHat" sensor tag in this paper along with presenting preliminary laboratory and field performance data."