We propose to build a compact, rugged field-deployable laser photoacoustic spectrometric (LPAS) sensor for continuous, real-time measurements of multiple chemical components, and perform field tests to qualify it for dynamic monitoring of Water Vapor, Carbon Dioxide (12CO2 and 13CO2), Carbon Monoxide, Methane, Ozone, Reactive and Trace Gases. Our sensor will be based on our laboratory LPAS instrument (at technology readiness level TRL-4)that has already demonstrated successful alcohol detection in presence of water vapor. It utilizes a tunable infrared laser (interband cascade or quantum cascade), a high sensitivity photoacoustic cell with an air sampler and an efficient algorithm to rapidly complete high sensitivity, selective multi-component measurements in under a minute. In Phase I we will carry out extensive laboratory tests of LPAS with standard samples, and a comprehensive analysis of the sensor performance using a model to determine the limit of detection (LOD) and receiver operating characteristic (ROC) curves for the sensor and establish its feasibility. A rugged and portable prototype sensor (TRL-5) will be built in Phase II. It will be field tested in open environment with artificially loaded target gases (TRL-6) and characterize the sensor.