Every possible source of air pollution is subject to increasing regulation either for worker safety, to maintain air quality for nearby residents, and/or as part of larger (national and international) pollution reduction strategies and protocols. Ambient air quality and toxics monitoring applications demand instruments capable of continuously monitoring multiple species in real time, often in remote or unattended locations. An instrument's utility is further enhanced if it can be deployed for months in the field without needing calibration or attention to replace consumables. Picarro WS-CRDS trace gas analyzers represent the forefront of monitoring technology. These rugged, compact instruments provide the ideal combination of accuracy, precision and long-term un-manned operation while being insensitive to contaminants and changing environmental conditions.