A system and method for detecting the presence of submicron sized particles in a sample taken from the environment includes a collecting a sample from the environment and purifying and concentrating the submicron particles in a sample based on the size of the particles. The purified and concentrated particles are detected with an apparatus which includes an electrospray assembly having an electrospray capillary, a differential mobility analyzer which receives the output from the capillary, and a condensation particle device for counting the number of particles that pass through the differential mobility analyzer. The system is intended to collect a sample containing submicron size particles having a size range of from greater than 350 nanometers to about 1000 nanometers and wherein the particles include viruses, prions, viral subunits, viral cores of delipidated viruses, plant viruses, standard particles used for calibrating equipment, coated particles, spherical particles, metallic-core shelled particles, polymers, fluorescent microspheres, powders, nanoclusters, particles produced as a result of manufacturing processes, and portions of bacteria.