The report describes the constituents of biological warfare agent detection systems. Warning detectors are working in real-time using physical principles. The warning detector often trigs a sample collector. The classification step is based on an indirect method to identify characteristic properties of micro-biological organisms. It can be working continuously (with some minutes delay) or on demand. These two stepts are non-specific, warning for any kind of biological activity. The last step - the indentification - gives specific information about possible biological warfare agents, or pathogenic microorganisms, in the air. Examples of detectors, instruments and prototypes are presented as well as integrated systems, where different detectors work together.