Method for enriching, preferably saturating, ordinary atmospheric air, referred to hereinafter as fresh air, with active substances present in gaseous phase, with volatile substances for deodorization, perfuming, disinfection and/or disinsection, characterized in that it comprises carrying out, in an airtight enclosure, the following operations: a) introducing gaseous fresh air not loaded with active substances into said enclosure, by means of a first ventilator at at least one inlet orifice of said enclosure, b) introducing it by at least one inlet into a plurality of enrichment or saturation chambers, for contacting said fresh air with at least one volatile active substance present in gaseous phase in order to enrich said air, preferably to saturation, with said volatile active substance or substances, c) withdrawing, at the outlet of said enrichment or saturation chambers, a portion of gaseous mixture enriched to a sufficient degree or saturated at the end of step b), by means of one or more compressors, for the purpose of storing it in an internal storage chamber or of evacuating it to the outside via one or more outlet orifices of said enclosure, d) re-injecting the portion of gaseous mixture not withdrawn in step c) or the entirety of said enriched or saturated gaseous mixture, into said enrichment or saturation chambers by means of a second ventilator so as to increase the degree of enrichment of said gaseous mixture, to maintain it at its maximum saturation level or to lower it by mixing it, in this case, before introduction into said enrichment or saturation chambers, with new, unloaded fresh air introduced from the outside into said enclosure, where the ratio between the stream of entering unloaded gaseous fresh air and the stream or streams of enriched or saturated gaseous mixture exiting the enclosure is greater than 1.5, and e) regulating the gaseous stream generated by the first and/or second ventilator (5, 6), so as to control the amount of volatile active substance diffused or withdrawn per unit time and unit surface area. a) introducing gaseous fresh air not loaded with active substances into said enclosure, by means of a first ventilator at at least one inlet orifice of said enclosure, b) introducing it by at least one inlet into a plurality of enrichment or saturation chambers, for contacting said fresh air with at least one volatile active substance present in gaseous phase in order to enrich said air, preferably to saturation, with said volatile active substance or substances, c) withdrawing, at the outlet of said enrichment or saturation chambers, a portion of gaseous mixture enriched to a sufficient degree or saturated at the end of step b), by means of one or more compressors, for the purpose of storing it in an internal storage chamber or of evacuating it to the outside via one or more outlet orifices of said enclosure, d) re-injecting the portion of gaseous mixture not withdrawn in step c) or the entirety of said enriched or saturated gaseous mixture, into said enrichment or saturation chambers by means of a second ventilator so as to increase the degree of enrichment of said gaseous mixture, to maintain it at its maximum saturation level or to lower it by mixing it, in this case, before introduction into said enrichment or saturation chambers, with new, unloaded fresh air introduced from the outside into said enclosure, where the ratio between the stream of entering unloaded gaseous fresh air and the stream or streams of enriched or saturated gaseous mixture exiting the enclosure is greater than 1.5, and e) regulating the gaseous stream generated by the first and/or second ventilator (5, 6), so as to control the amount of volatile active substance diffused or withdrawn per unit time and unit surface area.