The Pacific 2001 Air Quality Study (PAC2001) was conducted from 1 August to 31 September, 2001 in the Lower Fraser Valley (LFV), British Columbia, Canada. The study consisted of a number of research projects organized to address several issues related to ambient particulate matter and ozone. A special issue of Atmospheric Environment [Vol. 38(34), Nov 2004] describes the study objectives (Li, 2004) and the study results. The data sets available for download are provided in collaboration with the National Atmospheric Chemistry (NAtChem) Database and Analysis Facility of Environment and Climate Change Canada.