The proposal focuses on photoacid generators (PAGs) widely utilized in photolithography processes at semiconductor fabrication facilities, i.e., sulfonium and idiodonium salts (“onium” salts). In particular, it aims to: (i) elucidate the chemical structure of the main onium photodegradation products found in semiconductor effluents, (ii) develop analytical methods for the quantification of onium PAGs and their photolysis products, and (iii) characterize key environmental, safety and health (ESH) properties on these compounds.