This Small Business Innovation Research (SBIR) Phase II proposal is directed at the development of high-resolution, low-cost, low-weight, low-energy-consuming, stable sensors w;th parts per billion (ppb) resolution for environmental monitoring of ozone. Calibration curves show that the device will operate in a linear mode over the required range, and that concentration changes of less than 5 ppb 03 can be measured reliably. Short-term stability, temperature and humidity influences, the ozone concentration sensitivity as well as interfering gas signals were investigated in Phase I with encouraging results. In Phase ll, sensor and monitor prototype development to control producibility, sensitivity life, and sensor integration to multi-parameter devices will be expanded with a commercially viable miniaturized device that can be produced with a Phase lll partner, targeted. Initially targeted environmental monitoring and industrial safety markets are expected to be in the multi-million dollar range. Significant interest in ozone monitoring in offices and homes could generate markets far exceeding the volume of the initial markets. Cost-benefit estimations strongly support the proposed ozone sensor development. In addition sensor miniaturization will open up new product applications.