title: Hourly measurements of fine particulate sulfate and carbon aerosols at the Harvard-U.S. Environmental Protection Agency Supersite in Boston.
abstract: Hourly concentrations of ambient fine particle sulfate and carbonaceous aerosols (elemental carbon [EC], organic carbon [OC], and black carbon [BC]) were measured at the Harvard-U.S. Environmental Protection Agency Supersite in Boston, MA, between January 2007 and October 2008. These hourly concentrations were compared with those made using integrated filter-based measurements over 6-day or 24-hr periods. For sulfate, the two measurement methods showed good agreement. Semicontinuous measurements of EC and OC also agreed (but not as well as for sulfate) with those obtained using 24-hr integrated filter-based and optical BC reference methods. During the study period, 24-hr PM2.5 (particulate matter [PM] < or = 2.5 microm in aerodynamic diameter) concentrations ranged from 1.4 to 37.6 microg/m3, with an average of 9.3 microg/m3. Sulfate as the equivalent of ammonium sulfate accounted for 39.1% of the PM2.5 mass, whereas EC and OC accounted for 4.2 and 35.2%, respectively. Hourly sulfate concentrations showed no distinct diurnal pattern, whereas hourly EC and BC concentrations peaked during the morning rush hour between 7:00 and 9:00 a.m. OC concentrations also exhibited nonpronounced, small peaks during the day, most likely related to traffic, secondary organic aerosol, and local sources, respectively.
authors.affiliation: Department of Environmental Health, Harvard School of Public Health, Boston, MA, USA.
authors.forename: Choong-Min
authors.initials: CM
authors.lastname: Kang
authors.forename: Petros
authors.initials: P
authors.lastname: Koutrakis
authors.forename: Helen H
authors.initials: HH
authors.lastname: Suh
mesh_terms: D000395:Air Pollutants, Occupational / Q000032:analysis*; D000465:Algorithms; D001900:Boston; D002244:Carbon / Q000032:analysis*; D002940:Circadian Rhythm; D004784:Environmental Monitoring / Q000379:methods*; D052638:Particulate Matter / Q000032:analysis*; D012621:Seasons; D013431:Sulfates / Q000032:analysis*; D014481:United States; D014484:United States Environmental Protection Agency
chemical_list: D000395:Air Pollutants, Occupational; D052638:Particulate Matter; D013431:Sulfates; D002244:Carbon