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<p>Nineteen years of atmospheric composition measurements made at the University of Toronto Atmospheric Observatory (TAO; 43.66<span class="inline-formula">^∘</span> N, 79.40<span class="inline-formula">^∘</span> W; 174 m a.s.l.) are presented. These are retrieved from Fourier transform infrared (FTIR) solar absorption spectra recorded with an ABB Bomem DA8 spectrometer from May 2002 to December 2020. The retrievals have been performed for 14 species: <span class="inline-formula">O₃</span>, HCl, HF, <span class="inline-formula">HNO₃</span>, <span class="inline-formula">CH₄</span>, <span class="inline-formula">C₂H₆</span>, CO, HCN, <span class="inline-formula">N₂O</span>, <span class="inline-formula">C₂H₂</span>, <span class="inline-formula">H₂CO</span>, <span class="inline-formula">CH₃OH</span>, HCOOH, and <span class="inline-formula">NH₃</span> using the SFIT4 algorithm. The measurements have been archived in the Network for the Detection of Atmospheric Composition Change (NDACC) data repository in Hierarchical Data Format version 4 (HDF4) files following the Generic Earth Observation Metadata Standard (GEOMS) and are also publicly available on Borealis, the Canadian Dataverse Repository (<a href="https://doi.org/10.5683/SP2/VC8JMC">https://doi.org/10.5683/SP2/VC8JMC</a>, Yamanouchi et al., 2022). In this paper, we describe the instrumentation, the retrieval strategy, the vertical sensitivity of the retrievals, the quality assurance process, and the error analysis of the TAO FTIR measurements and present the current version of the time series.</p>