Source testing is the direct collection of gas, particulate or odour samples from a stack or vent. Source testing is fundamentally different from ambient air monitoring due to the significantly higher concentrations and possibly higher temperatures. It requires specialized methods and equipment to ensure that representative samples are collected. Stack sampling can be carried out for a variety of reasons, such as general assessments of emissions, or to verify compliance with permits or regulations. SENES routinely designs and manages source testing programs in various locations and applications.