Composition and sources of fine and coarse particles collected during 2002–2010 in Boston, MA
Creators: name: Koutrakis, Petros
name: Shahir Masri
name: Choong-Min Kang
Publisher: name: Taylor & Francis
Year: 2015
Subjects: subject: Science Policy
subject: Cancer
subject: Biological Sciences
subject: Chemistry
subject: Earth and Environmental Sciences
subject: Geology
subject: FOS: Earth and related environmental sciences
subject: FOS: Earth and related environmental sciences
subject: Biotechnology
subject: Microbiology
subject: FOS: Biological sciences
subject: FOS: Biological sciences
subject: Engineering

description: Identifying the sources, composition, and temporal variability of fine (PM<sub>2.5</sub>) and coarse (PM<sub>2.5–10</sub>) particles is a crucial component in understanding particulate matter (PM) toxicity and establishing proper PM regulations. In this study, a Harvard Impactor was used to collect daily integrated fine and coarse particle samples every third day for 9 years at a single site in Boston, MA. In total, 1,960 filters were analyzed for elements, black carbon (BC), and total PM mass. Positive Matrix Factorization (PMF) was used to identify source types and quantify their contributions to ambient PM<sub>2.5</sub> and PM<sub>2.5–10</sub>. BC and 17 elements were identified as the main constituents in our samples. Results showed that BC, S, and Pb were associated exclusively with the fine particle mode, while 84% of V and 79% of Ni were associated with this mode. Elements mostly found in the coarse mode, over 80%, included Ca, Mn (road dust), and Cl (sea salt). PMF identified six source types for PM<sub>2.5</sub> and three source types for PM<sub>2.5–10</sub>. Source types for PM<sub>2.5</sub> included regional pollution, motor vehicles, sea salt, crustal/road dust, oil combustion, and wood burning. Regional pollution contributed the most, accounting for 48% of total PM<sub>2.5</sub> mass, followed by motor vehicles (21%) and wood burning (19%). Source types for PM<sub>2.5–10</sub> included crustal/road dust (62%), motor vehicles (22%), and sea salt (16%). A linear decrease in PM concentrations with time was observed for both fine (–5.2%/yr) and coarse (–3.6%/yr) particles. The fine-mode trend was mostly related to oil combustion and regional pollution contributions. Average PM<sub>2.5</sub> concentrations peaked in summer (10.4 µg/m<sup>3</sup>), while PM<sub>2.5–10</sub> concentrations were lower and demonstrated little seasonal variability. The findings of this study show that PM<sub>2.5</sub> is decreasing more sharply than PM<sub>2.5–10</sub> over time. This suggests the increasing importance of PM<sub>2.5–10</sub> and traffic-related sources for PM exposure and future policies.Implications: <i>Although many studies have examined fine and coarse particle composition and sources, few studies have used concurrent measurements of these two fractions. Our analysis suggests that fine and coarse particles exhibit distinct compositions and sources. With better knowledge of the compositional and source differences between these two PM fractions, better decisions can be made about PM regulations. Further, such information is valuable in enabling epidemiologists to understand the ensuing health implications of PM exposure.</i>