"In 2009, DEQ created the Portland Air Toxics Solutions project to work with local communities to develop air toxics reduction strategies for the Portland region, including portions of Multnomah, Washington and Clackamas Counties" (www.deq.state.or.us/aq/toxics/pats.htm). These data represent block-group scale modeling of air toxics risks from a variety of sources (19 pollutants total), prepared in 2012 with model extrapolation to target year 2017. The study led to a number of priorities and ongoing management/policy discussions regarding Portland air quality. Data included here generally represent a ratio of pollutant concentration to ABC (ambient background concentration) for that pollutant, implying relative risk from each pollutant; see attribute file for details.