Emitted into the atmosphere biogenic and anthropogenic volatile organic compounds (VOCs) are oxidized with OH radicals (day-time chemistry) and NO₃ radicals (night-time chemistry) as well as ozone forming semi-volatile organic compounds that undergo gas-to-particle conversion leading to SOA formation. (Hallquist et al., 2009).  The chemistry taking place during the day-time strongly influences the subsequent night-time chemistry and vice versa. Therefore, day-time and night-time chemistry cannot be considered separately but influence each other. Therefore, using aerosol smog chamber the chemical processing of α-pinene was developed to investigate the interconnection of day- and night-time chemistry.

Teflon reactors, known as smog or atmospheric simulation chambers, have been valuable research tools for the study of the complex chemical interactions that take place in the atmosphere. Studies using such reactors eliminate many of the uncertainties resulting from the analysis of ambient observations where several variables, such as complexity of aerosol composition, weather conditions, pollutant emission rates, dilution transport have to be considered.