Polycyclic aromatic hydrocarbons (PAHs) are chemical compounds that consist of fused aromatic rings and do not contain heteroatoms or carry substituents. PAHs are one of the most widespread organic pollutants. Their occurrence is largely a result of anthropogenic and natural emissions such as fossil fuel-burning, motor vehicle, waste incinerator, oil refining, coke and asphalt production, and aluminum production. This book examines recent developments in the field.