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The Atlanta Aerosol (in 10 min). Rodney Weber Georgia Tech rweber@eas.gatech.edu 404-894-1750, www.aerosols.eas.gatech.edu. Atlanta and the PM2.5 NAAQS. From: Eric Edgerton, ARA Inc. Atlanta. Yorkville rural pair. Aerosol Chemistry. Need aerosol chemistry to study PM sources
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The Atlanta Aerosol(in 10 min) Rodney Weber Georgia Tech rweber@eas.gatech.edu 404-894-1750, www.aerosols.eas.gatech.edu
Atlanta and the PM2.5 NAAQS From: Eric Edgerton, ARA Inc. Atlanta Yorkville rural pair
Aerosol Chemistry • Need aerosol chemistry to study PM • sources • health effects • PM2.5 Mostly • Sulfate • Carbonaceous • Organic • Elemental (Soot)
Sulfate Aerosol SO2 from coal-fired power plants. (EPA; Document 454-R-04-002) Industrial/Institutional energy production,... Emissions also includes toxic substances, e.g., mercury
Sulfate Aerosol Local Sulfate Regional Sulfate Power plants lead to large localized PM
Surface PM spikes often driven by sulfate ~ 40 High degree of short-term variability (PM2.5 can double in a few hours) 24 h vs 1 h avg. Jefferson Street, Atlanta (rain) (rain)
Sulfate Aerosol Summary • Sulfate is a large fraction of Atlanta PM2.5 • implications for meeting NAAQS. • Characterized by regional w/ superimposed local emissions. • Possible links between transient PM and Myocardial Infarction (Peters et al., Circulation 2001, 103: 2810-15) • Transient PM not observed in 24-hr averages • No hourly PM standard
Carbonaceous Aerosol Primary (insoluble) + Secondary (soluble) • Organic and Elemental Carbon • Mainly from internal combustion engines + OC biogenic sources • Also includes toxic substances, e.g., aromatic VOCs, PAHs, metals
Exposure to Carbonaceous Aerosol and Proximity to Highways Geographical - Carbonaceous Georgia Tech vs 75/85 Georgia Institute of Technology (GIT) Roof top of ES&T Building Next to I-75/85 ~ 400 m from GIT and ~1 m from highway V.S.
400 m Georgia Tech vs 75/85 June 15-18, 2005 Uncertainty is 5%, based on side by side comparisons 11 7.8 4.5 4.7 4.3 0.5 (soot) (Water-Soluble) EC: 9 times higher at road (EC is all primary) OC: 1.4 times higher at road (mainly due to insoluble primary) WSOC: Little difference (WSOC is almost all secondary)
Atlanta vs Rural Comparison on a larger spatial scale Georgia Institute of Technology (GIT) Roof top of ES&T Building Yorkville, GA ~80 km west of GIT V.S.
Atlanta vs Rural July 23-27, 2005 Directly emitted (primary) carbonaceous aerosol higher in Atlanta Secondary (water-soluble) organic carbon spatially uniform
Carbonaceous Aerosol 1. OC large fraction of Atlanta PM2.5 -implications for meeting NAAQS. 2. Importance of location depends on what components of carbonaceous aerosol are health risks: a) Primary components (primary OC & EC - apparent risk) • tends to be water-insoluble (pure HCs) • spatially non-uniform • sources fairly well known. b) Secondary components (health risk??, 60-75% of OC in summer) • tends to be soluble in water (oxygenated-HCs) • spatially uniform • source not well known (mainly unknown chemical comp.) • linked to biogenic VOCs (terpenes/isoprene: trees) ? • linked to vehicle emissions ? • Implications on how to regulate.