Table 1 Studies evaluating the contribution of aromatic hydrocarbons to SOA

[20]

Contribution of primary and secondary sources of OC to PM_2.5 in a small subset of Southeastern Aerosol Research and Characterization (SEARCH) network samples

(2,3-hydroxy-4-oxopentanoic acid used as a chemical tracer for aromatic SOA

0.10 to 0.45 across 4 sampling locations

[21]

Contribution of primary and secondary sources of OC to PM_2.5 in five midwestern United States cities year–round: East St. Louis, IL Detroit, MI Cincinnati, OH Bondville, IL and Northbrook, IL

2,3-hydroxy-4-oxopentanoic acid used as a chemical tracer for aromatic SOA

Bondville: 0.09 - 0.25; Northbrook: 0.06 - 0.21; Cincinnati: 0.02 - 0.29; Detroit: 0.07 - 0.33; East St. Louis: 0.06 - 0.26

[22]

Contribution of primary and secondary sources of OC to PM_2.5 in 2006 in Research Triangle Park, NC over the course of a year

2,3-hydroxy-4-oxopentanoic acid used as a chemical tracer for aromatic SOA

average = 0.1, stdev = 0.09, min = 0.02, max = 0.36, n = 33

[33]

Positive matrix factorization of organic marker measurements to estimate primary and secondary components of organic aerosol

SOA from motor vehicles contribute 11% of total organic aerosols

method is not quantitative

[23]

Contribution of primary and secondary sources of OC to PM_2.5 in July-August 2007 in Cleveland, OH, Detroit, MI and LA, CA

2,3-hydroxy-4-oxopentanoic acid used as a chemical marker for aromatic SOA, using a different analytical method than [20–22]

0.05 - 1.1 in the midwest; 0.95 - 1.61 in CA