This paper reviews the transformation processes that polycyclic aromatic hydrocarbons
(PAHs) undergo in the atmosphere. These processes can take place both in the gas phase
and in the particulate/aerosol one. Among the gas‐phase processes, the most important
ones are the daytime reaction with• OH and the nighttime reaction with• NO3. The relative
importance of the two processes depends on the particular PAH molecule. For instance,
gaseous naphthalene is mainly removed from the atmosphere upon reaction with• OH, while …

This is the first of a series of two papers intended to review the state‐of‐the‐art knowledge
on atmospheric PAHs, concerning their monitoring, sources and transformation processes in
the atmosphere. The monitoring section briefly introduces this class of compounds, mainly
focusing on the 16 PAHs indicated by the US‐EPA as priority pollutants. These compounds
undergo partitioning between the gas phase and particulate, which has to be considered in
the choice of the sampling methodology. Furthermore, sampling artifacts may arise from …