Pyrene of natural and anthropogenic sources is one of the toxic, mutagenic polycyclic aromatic hydrocarbons (PAHs) listed as priority pollutants. The recalcitrant nature of pyrene and other PAHs lies in part in their low solubility in water, rendering them less susceptible to chemical or biological degradation. This work investigates the use of a polar-nonpolar (PNP) solvent system, in conjunction with ozonation, to overcome this remediation obstacle. The PNP solvent system consists of equal portions of polar acetic acid and nonpolar heptane. The heptane component enables high concentrations of pyrene to be dissolved, while the acetic acid keeps subsequently formed polar intermediates and byproducts in solution. This PNP solvent system maintains effective exposure of all compounds to aqueous ozone throughout the course of reaction and prevents the formation of solid precipitation. Following ozonation, the solvent system is added with a small amount of water that results in the formation of two distinct phases. The lighter upper heptane phase contains any remaining parent pyrene and little if any hydrophilic intermediates, whereas the heavier lower aqueous acetic acid solution accommodates a plethora of polar intermediates formed during ozonation. The intermediates-laden acetic acid solution (e.g., 95% water) is further subject to biochemical oxygen demand (BOD) and Escherichia coli toxicity tests to assess the inhibitory effect of the intermediates. The results suggest that for a heavy load of pyrene (e.g., 600 mg/L) in the PNP solvent system, brief ozonation treatment (e.g., 10-20 min) removes virtually all pyrene and significantly decreases the toxicity of the intermediates, as evidenced by increased BOD measured in the effluent; this is further corroborated by a decrease in E. coli inhibition by the intermediates from -15.8% in the toxic range to -3.27% in the nontoxic range. The PNP solvent proves useful as a medium to effectively facilitate ozone attacks on hydrophobic, recalcitrant contaminants as well as any concomitant, polar intermediates throughout the entire course of reaction.