PM Dimensional Characterization in an Urban Mediterranean Area: Case Studies on the Separation between Fine and Coarse Atmospheric Aerosol

Maurizio Manigrasso,Maria Eleonora Soggiu,Gaetano Settimo,Matteo Vitali,Marco Inglessis,Carmela Protano,Pasquale Avino

doi:10.3390/atmos13020227

Abstract

Fine particulate matter (PM) is object of particular attention due to its health effects. It is currently regulated by adopting PM2.5 as an indicator to control anthropogenic combustion emissions. Therefore, it is crucial to collect aerosol samples representative of such sources, without including PM from natural sources. Thus, a clean separation between coarse and fine mode aerosol should be set. With this purpose, aerosol size mass distribution was taken in the aerodynamic diameter range from 0.5 to 10 µm. In comparison with a base scenario, characterized by local pollution sources, three case studies were considered, involving desert dust advection, sea salt advection and forest fire aerosol from a remote area. In the base scenario, PM2.5 represented a suitable fine-mode indicator, whereas it was considerably affected by coarse PM in case of desert dust and sea salt aerosol advection. Such interference was considerably reduced by setting the fine/coarse separation at 1.0 µm. Such separation underrepresented fine PM from forest fire long-range transport, nonetheless in the case studies considered, PM1 represented the best indicator of fine aerosol since less affected by coarse natural sources. The data presented clearly support the results from other studies associating the health effects of PM2.5 to PM1, rather than to PM1–2.5. Overall, there is a need to reconsider PM2.5 as an indicator of fine atmospheric aerosol.

Highlights

Particulate matter (PM) atmospheric pollution started becoming a serious health problem at the beginning of the 19th century, when steadily increasing industrialization caused the release into the atmosphere of growing amounts of pollutants
The purpose of this paper is to investigate how the aerosol sources that determine particulate matter (PM) pollution in an urban area contribute to PM2.5 and PM1 concentrations and where the cut-off point between fine anthropogenic combustion aerosol and coarse aerosol from natural sources could be properly set
We have considered a basic scenario (February 2012), where aerosol pollution was determined by local sources and three other scenarios characterized by the additional contribution of aerosol from remote areas: (i) desert dust advection (January 2013), (ii) sea salt aerosol advection, (April 2009) (iii) forest fire burning (April 2020)

Summary

Introduction

Particulate matter (PM) atmospheric pollution started becoming a serious health problem at the beginning of the 19th century, when steadily increasing industrialization caused the release into the atmosphere of growing amounts of pollutants. It was in 1987 that PM10 limits were set for the first time by the United States Environmental Protection Agency (USEPA) (52 FR 24634) and in 1999 by the European Union (EU) [1]. Human exposure to high PM10 levels has been associated to different adverse health effects involving the cardiovascular and respiratory systems, especially in subjects with pre-existing diseases; besides, PM10 exposure can be determine lung cancer, and various kind of allergies [2,3,4,5]. PM2.5 has been recognized as one of the main environmental risk factors, contributing to several adverse negative outcomes for human health impacts such as cerebrovascular diseases, chronic obstructive pulmonary disease, lung cancer, lower respiratory infections among the young and premature mortality cases [12,13,14,15,16]

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