Chlorine (Cl2) is a highly toxic gas that is also widely used industry. Workers in wastewater, paper, semiconductors, chemical plants and laboratories may encounter chlorine frequently. Chlorine is also has been used in chemical warfare. Gas detectors must be sensitive to detect low concentrations (less than 1 ppm), stable and resistant to interfering gases. Monitoring for Chlorine help prevent accidents through on-body and distributed sensing applications.