The Task Force on Hemispheric Transport of Air Pollution met at IASS Potsdam, Germany, on April 25-26 2019. Approximately 30 people attended the meeting, including representatives of TF IAM and CIAM, who had just attended the 48th meeting of TF IAM in Berlin over the previous 2 days. Terry Keating (US Environmental Protection Agency, TF HTAP chair) chaired the meeting. Tim Butler (IASS Potsdam, local organiser) welcomed TF HTAP to Potsdam and opened the meeting.