A system and a method to detect biological and chemical agents in a sealed contained at, for example, a mail-processing center. The system includes filtration and vacuum subsystems cooperatively working to draw an air sample from the interior of the particulate containment system for evaluation by a biosensor or chemical analyzer to detect the presence of a contaminant. The vacuum subsystem includes a vacuum generator, flow meters, and pressure regulators to accommodate the varying volume within the particulate containment system. The filtration system includes an inlet filter and a high efficiency particle air filter (HEPA) filter. The inlet filter removes coarse impurities, such as dust and dirt, from the incoming air to improve sensor efficiency. The HEPA removes contaminants from the air sample prior to being released to the surrounding environment, thereby eliminating the possibility of spreading the contamination outside the particulate containment system. Additionally, an agitating means is connected to the particulate containment system to loosen contaminants and create a contaminated air cloud, thereby increasing the concentration of contaminants in the interior of the particulate containment system to facilitate air sampling. The agitation can be performed using rectilinear motion or rotary motion. When rotary motion is used, the system includes a rotary cylinder having radially extending chambers for holding tubs of bulk mail, which tubs become agitated during the rotary cycle of the cylinder, thereby allowing for controlled release of contaminants within the tub. Samples of air from within the tub are tested for hazardous materials. Tubs having uncontaminated mail continue downstream for further processing and handling.