Ambient air and soil concentrations of PAHs and PCBs were investigated in a megacity; Istanbul in Turkey. The PAH concentrations were higher at urban and industrial sites. However, PCBs showed moderately uniform variations. Fugacity ratio result showed that source/sink tendency of PAHs and PCBs depends on their volatility and temperature. Toxicological effect study revealed the severity of the air and soil pollution especially in terms of PAHs in Istanbul.