This report documents outdoor trials with biological aerosol detectors realized in Sweden between March 14 and 18, 2005. The objective of these trials was to test the detection capacities of biological detectors in conditions close to reality. The trials were performed under winter conditions. One of the present detectors was a serial MAB (Biological Aerosol Monitor, Proengin S.A. France). In most of the cases, the MAB results compared with those of the reference instruments. The MAB was able to: 1. Discriminate between the particles of the background and of those whose signature corresponds to the biologic family; 2. Discriminate between the bioaerosols even when they are mixed with inert particles; 3. Count particles if they are not biological and contain emissive elements; 4. Classify bioaerosols of the biosimulants BG and BT in two different groups; 5. Detect ovalbumin which is a molecule used when simulating toxin. As appears from the report, the MAB did not show any observable memory effect. When detecting a cloud, the signal dropped rapidly as the cloud disappeared. In none of the cases was MAB saturated and could detect biological aerosol directly or even during a simulated high background of mineral particles.