Volume 2: Draft Gorst Planned Action Environmental Impact Statement

GORST PLANNED ACTION EIS | AFFECTED ENVIRONMENT, SIGNIFICANT IMPACTS, AND MITIGATION MEASURESfocus on the size fractions thought to be most dangerous to people. At present, there are standards for particulatematter less than 10 micrometers in size (PM10) and particulate matter less than 2.5 micrometers in size (PM2.5),because these sizes of particulate contribute the most to human health effects, regional haze, and acid deposition.The highest ambient concentrations generally occur near the emissions sources, which in the Gorst study areawould be motor vehicle tailpipes from SR 3, SR 16, and major roads. PM2.5 has a greater impact than PM10 atlocations far from the emitting source, because it remains suspended in the atmosphere longer and travels farther.Air Quality Attainment StatusBased on monitoring information collected over a period of years, the EPA and Ecology designate regions as beingattainment or nonattainment areas for regulated air pollutants. Attainment status indicates that air quality in anarea meets the National Ambient Air Quality Standards (NAAQS), and nonattainment status indicates that airquality in an area does not meet those standards. If the measured concentrations in a nonattainment area improveso they are consistently below the NAAQS, Ecology and EPA can reclassify the nonattainment area to amaintenance area.The Gorst study area is currently designated as an attainment area for all criteria air pollutants (ozone, CO, PM10,PM2.5, lead, sulfur dioxide [SO2], and NO2). Additionally, the Gorst study area is not located within a maintenancearea. In March 2008, the EPA lowered its 8-hour ozone standard from 0.08 parts per million (ppm) to 0.075 ppm tobetter protect public health. In January 2010, EPA proposed a revision to the 2008 ozone standard, and put all areadesignations to the 2008 standard on hold. Until the revised standard is adopted, the region is still designated anattainment area for ozone.Similarly, in 2010, EPA enacted a new, more stringent 1-hour average ambient air quality standard for NO2. At thistime it is not known which regions in the country will be re-designated based on the new standard. Therefore, asof this time, the Gorst study area is still considered an attainment area for NO2.Air Toxics IssuesThe Gorst study area includes residential, commercial, and light industrial uses that pose no special issues relatedto air toxics. Although the Gorst study area is not near any major industrial facilities that emit large amounts oftoxic air pollutants, SR 3 and SR 16 pass through the Gorst study area, and heavy diesel trucks traveling along thehighways have the potential to emit toxic air pollutants. It is expected that existing and future air quality in theGorst study area adjacent to SR 3 and SR 16 could be affected by moderate concentrations of toxic air pollutants.According to EPA’s National Air Toxics Assessment 2005 database, the existing respiratory cancer risk in the censustracts that includes the Gorst study area is roughly 37 x 10 -6 or 37 cancer cases per million population (EPA 2013).This reported respiratory cancer risk is typical of other rural areas in Washington State.PSRC Transportation Conformity AnalysisUnder federal and state regulations, PSRC is required to demonstrate that the Regional Transportation Plan (RTP)or Transportation Improvement Program (TIP) conforms to the State Implementation Plan allowable emissionsbudget. The State Implementation Plan provides a blueprint of how maintenance and nonattainment areas such asthe central Puget Sound region will meet or maintain the NAAQS. The most recent air quality analysis (PSRC 2013)for the 2013–2016 Regional TIP and the long-range RTP, demonstrates that 2040 forecasted regional emissionsconform to the State Implementation Plan’s allowable emissions budgets.National Ambient Air Quality StandardsEPA establishes NAAQS and specifies future dates for states to develop and implement plans to achieve thesestandards. The standards are divided into primary and secondary standards; the former are set to protect humanhealth within an adequate margin of safety, and the latter to protect environmental values, such as plant andanimal life. Table 3.3-1 National and Washington State Ambient Air Quality Standards lists the NAAQS for sixcriteria pollutants: CO, ozone, PM10, PM2.5, lead, SO2, and NO2.Draft | June 2013 3-27