Aims: A portable bioaerosol monitor is greatly demanded technology in many areas including air quality control, occupational exposure assessment and health risk evaluation, environmental studies and, especially, in defence and bio-terrorism applications. Our recent groundwork allowed us to formulate the concept of a portable bioaerosol monitor, which needs to be light, user friendly, reliable and capable of detecting airborne pathogens within 1-1.5 h on the spot. Methods and Results: Conceptually, the event of a bioaerosol concentration burst is determined by triggers to commence the representative air sampling with sequential real-time polymerase chain reaction (PCR) confirmation of the targeted micro-organism present in the air. To minimize reagent consumption and idle running of the technology, an event of a bioaerosol burst is confirmed by three parameters: aerosol particle size, concentration and composition. Only particle sizes above 200 nm attract interest in the bioaerosol. Only an elevated aerosol concentration above the threshold (background aerosol concentration) is a signal to commence the analytical procedure. The combination of our previously developed personal bioaerosol sampler, aerosol particle counter based trigger and portable real-time PCR device formed the basis of the bioaerosol monitoring technology. The portable real-time PCR device was advanced to provide internally controlled detection, significantly reducing false-positive alarms. Conclusions: The technique is capable of detecting selected airborne microorganisms on the spot within 30-80 min, depending on the genome organization of the particular strain. Significance and Impact of the Study: Due to recent outbreaks of infectious airborne diseases and the continuing threat of intentionally released bioaerosol attacks, investigations into the possibility of the early and reliable detection of pathogenic micro-organisms in the air is becoming increasingly important. The proposed technology consisting of a bioaerosol sampler, technology trigger and PCR device is capable of detecting selected airborne micro-organisms on the spot within a short time period.