An air filtration device for suppressing biological pollutants for closed environments, of the type that can be associated with the air outlets in ventilation, climate control and similar devices and systems, comprising at least one box-like enclosure (2) provided with at least one inlet (2a) for the air to be filtered, at which at least one perforated conducting grille (3) is located, the grille(3) having a preset negative electrical potential and being adapted to emit electrons when air flows, so as to give a negative electric charge to the particles to which the microorganisms (A) presentin the air adhere, the device (1) forming internally at least one air passage duct, which is formed between at least one plate (4) for collecting the negatively charged particles to which the microorganisms (A) adhere, the collector plate (4) having a predefined positive potential, and at least one deflector plate (5), which has a negative potential and is adapted to divert the particles to whichthe microorganisms (A) adhere, an electrical field being generated between the collecting plate (4) and the deflector plate (5), which face each other, the field being adapted to divert and precipitate the particles to which the microorganisms (A) adhere onto the collector plate (4), means (6) for inactivation of the microorganisms being provided and at least one outlet (2b) for the filtered air being also provided.