To extrapolate the viscosity results from our study to the atmosphere we combined annual average RH and temperature values in the troposphere with the parameterizations for viscosity as a function of RH and temperature (Fig. ) following the approach used previously. Annual average tropospheric RH and temperature values were extracted from the European Center Hamburg Model/Modular Earth Submodel System Atmospheric Chemistry Model. The results of this extrapolation are presented in Fig. for guaiacol-NO 3 SOA and guaiacol-OH SOA.