An apparatus comprising: an evaporation assistance element; a delivery engine positioned within a housing and downstream of said evaporation assistance element, wherein said delivery engine comprises: a reservoir containing a perfume mixture comprising an olfactive index ("OI") of at least about 12,000, wherein said perfume mixture comprises at least about 5 wt.% of perfume raw materials ("PRM"s) having an odor detection threshold ("ODT") less than or equal to about 1 ppb, and said perfume mixture comprises about 45 wt.% to about 85 wt.% of PRMs having a weighted average VP range from about 15,000 ppb to about 20,000 ppb; and a fluid transport member ; wherein said evaporation assistance element is configured to evaporate said perfume mixture into the atmosphere; wherein a PRM is a material adding perfume to the perfume mixture; wherein OI is calculated by the equation: OI = ∑ i x i ⋅ P vap , i sat , 25 C ODT i where P vap , i sat , 25 C is a saturation vapor pressure (VP) of a volatile PRMi at 25°C expressed in units of ppb; x i is the molar percent of the PRM i in the perfume composition; and ODT i is the odor detection threshold of the PRM i expressed in units of ppb and where all PRMs in the perfume composition are included in the calculated OI value; where the ODT value is calculated using a computational model generated from the molecular structure of each PRM. an evaporation assistance element; a delivery engine positioned within a housing and downstream of said evaporation assistance element, wherein said delivery engine comprises: a reservoir containing a perfume mixture comprising an olfactive index ("OI") of at least about 12,000, wherein said perfume mixture comprises at least about 5 wt.% of perfume raw materials ("PRM"s) having an odor detection threshold ("ODT") less than or equal to about 1 ppb, and said perfume mixture comprises about 45 wt.% to about 85 wt.% of PRMs having a weighted average VP range from about 15,000 ppb to about 20,000 ppb; and a fluid transport member ; a reservoir containing a perfume mixture comprising an olfactive index ("OI") of at least about 12,000, wherein said perfume mixture comprises at least about 5 wt.% of perfume raw materials ("PRM"s) having an odor detection threshold ("ODT") less than or equal to about 1 ppb, and said perfume mixture comprises about 45 wt.% to about 85 wt.% of PRMs having a weighted average VP range from about 15,000 ppb to about 20,000 ppb; and a fluid transport member ; wherein said evaporation assistance element is configured to evaporate said perfume mixture into the atmosphere; wherein a PRM is a material adding perfume to the perfume mixture; wherein OI is calculated by the equation: OI = ∑ i x i ⋅ P vap , i sat , 25 C ODT i where P vap , i sat , 25 C is a saturation vapor pressure (VP) of a volatile PRMi at 25°C expressed in units of ppb; x i is the molar percent of the PRM i in the perfume composition; and ODT i is the odor detection threshold of the PRM i expressed in units of ppb and where all PRMs in the perfume composition are included in the calculated OI value; where the ODT value is calculated using a computational model generated from the molecular structure of each PRM. <EOS>