Res 2021-102/approving a commitment to support the CAPCOG Clean Air Coalition's proposed Regional PM2.5 Emission Reduction and Planning Measures for the Austin-Round Rock-Georgetown MSA Regional Air Quality Plan

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Proposed Regional PM2.s Emission Reduction and Planning Measures for the Austin -Round Rock -Georgetown MSA Regional Air Quality Plan — February 25, 2021 Appendix A: Additional Background What are the Health Effects of Particulate Matter Pollution? Particles with diameters of 2.5 micrometers or smaller (PM2.5, or "fine PM") are small enough to penetrate and harm numerous body systems. EPA's review of PM health studies have indicated "causal" or "likely causal" relationships between short-term and/or long term exposure to PM2.5 and the following health effects': • Premature death; • Lung cancer; • Cardiovascular effects; • Nervous system effects; and • Respiratory effects. EPA's review also indicated that there is no evidence of a threshold below which further reductions to PM2.5 exposure would not continue to decrease risks. This means that there are public health benefits of reducing both long-term and short-term exposure to PM2.5 even if an area is attaining the PM2.5 NAAQS. EPA also reviewed health effects of particles with diameters 2.5 —10 micrometers (PM2.5-10 or "coarse PM), but EPA was not able to determine if particles in this size range could be definitively linked to any health outcomes. EPA does have a NAAQS for short-term exposure to all particles with diameters 10 micrometers or smaller (PM1o), but PM10 includes PM2.5• EPA also reviewed information on health effects associated with even smaller particles — ones with diameters smaller than 0.1 micrometers (PMo.1 or "ultrafine PM"), but was not able to determine conclusively if there were health effects from particles these sizes that were distinct from the health effects it assessed for PM2.5. Who is Most Affected by Particulate Matter Pollution? People with heart or lung diseases, children, and older adults are the most likely to be affected by PM2.5 pollution exposure. These sensitive groups comprise at least 40% of the population in the MSA. Additionally, people of color and people with low incomes tend to have disproportionate exposure to high PM2.5 levels. What are the Different Types of PM2.�:, Pollution? PM2.5 is both a primary pollutant (i.e., directly emitted from different sources) and a secondary pollutant (i.e., formed in the atmosphere through chemical reactions and processes from other direct emissions). Sources of PM2.5 include: • Crustal PM2.5 — particles from dust/soil; • Elemental carbon (EC) PM2.5 — particles that contain the elemental form of carbon (i.e., graphite); • Organic carbon (OC) PM2.5 — particles that contain organic molecules (hydrocarbons); • Sulfate PM2.5 — particles that contain SO4 molecules; • Nitrate PM2.5 — particles that contain NO3 molecules; and • Ammonium PM2.5 — particles that contain NH4 molecules. Which Type of PM2.;, Pollution is of Most Concern? The type of PM2.5 that appears to be contributing the most to the highest levels of annual PM2.5 concentrations within the region is organic carbon PM2.5. The large variation in the organic carbon PM2.5 contributions at the two regional regulatory monitors in 2014-2018 accounts for the vast majority in the differences in the annual PM2.5 concentrations between these locations. This suggests that reducing organic carbon PM2.5 emissions would ' EPA. Integrated Science Assessment for Particulate Matter. December 2019. EPA/600/R-19/188, httr)://ofmi)ub.er)a.gov aims eimscomm. etfile? download id=539935. Page 4 of 10