This project will assess the potential of state of the art optical spectroscopic techniques for traceable AMC monitoring in cleanroom environments and how advanced optical techniques will impact on the detection of smaller AMC quantities. Therefore, this project has the following objectives: To develop ultra‑sensitive and real‑time spectroscopic methods for the detection of critical airborne molecular contaminants (AMCs) (e.g. NH3, HCl and water vapour) with target detection values for HCl lower than 1 nmol/mol and in less than 1 minute. In addition, to determine the optimal spectral windows for such techniques based on High Resolution Transmission (HITRAN) calculations and component availability. To develop traceable static and dynamic reference materials for use with real time monitoring for priority AMCs in a nitrogen matrix at less than 1 nmol/mol, specifically static and dynamic references and for HCl at 10 μmol/mol, using methods to produce dilutions higher than 10000:1 for AMCs with a target accuracy better than 0.5 % relative. In addition to develop instrumentation and novel passivation techniques to optimise the long‑term stability of static reference materials for AMCs. To compare and perform field tests of different spectroscopy techniques for real‑time AMC detection, including an investigation of typical AMC monitoring scenarios (e.g. monitoring filter breakthrough and confined environments). The target time resolution for the spectroscopy techniques is better than 5 min and with a sensitivity lower than 1 nmol/mol for AMCs. To develop traceable dynamic or static gas transfer standards for AMCs and opto‑analytical transfer standards for the validation of measurement techniques commonly used in cleanrooms (e.g. ion‑mobility spectrometry), including the use of in‑situ calibration techniques. To facilitate the take up of the technology and measurement infrastructure developed in the project by the measurement supply chain (e.g. accredited laboratories and instrument manufacturers), standards developing organisations (e.g. ISO TC 158, CEN TC 264, International Society for Automation (ISA) Standard 71.04‑1985 and standards bodies associated with European Waste Incineration Directive 2000/76/EC and the Ambient Air Quality Directive 2008/50/EC) and end users (e.g. the semiconductor and electronics industries).