Airborne Particulate Matter: Sources, Atmospheric Processes and Health (Issues in Environmental Science and Technology, Volume 42) - Hardcover

Hardcover

ISBN 10: 1782624910 ISBN 13: 9781782624912

Publisher: Royal Society of Chemistry, 2016

Synopsis

The estimated health impacts and associated economic costs resulting from airborne particulate matter are substantial. Exposure to airborne fine particles ranks highly amongst preventable causes of disease. This book reviews the sources and atmospheric processes affecting airborne particulate matter and consequent impacts upon human health. Examining the latest information on the sources of particles in the atmosphere, both through direct emissions and atmospheric formation, the book also explores the methods which are used to estimate the contributions of different sources to airborne concentrations. Featuring case studies from recent assessments in Europe, the USA, China and India, the book provides a global overview of source apportionment. The health effects are reviewed in the context of the influence of sources, chemical composition and particle size upon relative toxicity. This comprehensive book is an important reference for policymakers and consultants working with pollution and human health, as well as academics working in atmospheric chemistry.

About this title

About the Authors

Roy Harrison OBE is Queen Elizabeth II Birmingham Centenary Professor of Environmental Health at the University of Birmingham. In 2004 he was appointed OBE for services to environmental science. Professor Harrison’s research interests lie in the field of environment and human health. His main specialism is in air pollution, from emissions through atmospheric chemical and physical transformations to exposure and effects on human health. Much of this work is designed to inform the development of policy.

Ron Hester is an emeritus professor of chemistry at the University of York. In addition to his research work on a wide range of applications of vibrational spectroscopy, he has been actively involved in environmental chemistry and was a founder member of the Royal Society of Chemistry’s Environment Group. His current activities are mainly as an editor and as an external examiner and assessor on courses, individual promotions, and departmental/subject area evaluations both in the UK and abroad.

From the Back Cover

The estimated health impacts and associated economic costs resulting from airborne particulate matter are substantial. Exposure to airborne fine particles ranks highly amongst preventable causes of disease. This book reviews the sources and atmospheric processes affecting airborne particulate matter and consequent impacts upon human health.

Examining the latest information on the sources of particles in the atmosphere, both through direct emissions and atmospheric formation, the book also explores the methods which are used to estimate the contributions of different sources to airborne concentrations. Featuring case studies from recent assessments in Europe, the USA, China and India, the book provides a global overview of source apportionment. The health effects are reviewed in the context of the influence of sources, chemical composition and particle size upon relative toxicity.

This comprehensive book is an important reference for policymakers and consultants working with pollution and human health, as well as academics working in atmospheric chemistry.

From the Inside Flap

The estimated health impacts and associated economic costs resulting from airborne particulate matter are substantial. Exposure to airborne fine particles ranks highly amongst preventable causes of disease. This book reviews the sources and atmospheric processes affecting airborne particulate matter and consequent impacts upon human health.

Examining the latest information on the sources of particles in the atmosphere, both through direct emissions and atmospheric formation, the book also explores the methods which are used to estimate the contributions of different sources to airborne concentrations. Featuring case studies from recent assessments in Europe, the USA, China and India, the book provides a global overview of source apportionment. The health effects are reviewed in the context of the influence of sources, chemical composition and particle size upon relative toxicity.

This comprehensive book is an important reference for policymakers and consultants working with pollution and human health, as well as academics working in atmospheric chemistry.

Excerpt. © Reprinted by permission. All rights reserved.

Airborne Particulate Matter

Sources, Atmospheric Processes and Health

By R.E. Hester, R. M. Harrison, X. Querol

The Royal Society of Chemistry

Copyright © 2016 The Royal Society of Chemistry
All rights reserved.

ISBN: 978-1-78262-491-2

Contents

Editors, xiii, 
List of Contributors, xv, 
Emissions of Primary Particulate Matter M. Guevara, 1, 
Where Did This Particle Come From? Sources of Particle Number and Mass for Human Exposure Estimates Neil M. Donahue, Laura N. Posner, Daniel M. Westervelt, Zhongju Li, Manish Shrivastava, Albert A. Presto, Ryan C. Sullivan, Peter J. Adams, Spyros N. Pandis and Allen L. Robinson, 35, 
Source Apportionment: Principles and Methods J. G. Watson, J. C. Chow, L.-W. A. Chen, G. Engling and X. L. Wang, 72, 
Case Studies of Source Apportionment from North America Philip K. Hopke, 126, 
Case Studies of Source Apportionment and Suggested Measures at Southern European Cities F. Amato, F. Lucarelli, S. Nava, G. Calzolai, A. Karanasiou, C. Colombi, V. L. Gianelle, C. Alves, D. Custodio, K. Eleftheriadis, E. Diapouli, C. Reche, A. Alastuey, M. C. Minguillon, M. Severi, S. Becagli, T. Nunes, M. Cerqueira, C. Pio, M. Manousakas, T. Maggos, S. Vratolis, R. M. Harrison and X. Querol, 168, 
PM10 Source Apportionment in Five North Western European Cities — Outcome of the Joaquin Project Dennis Mooibroek, Jeroen Staelens, Rebecca Cordell, Pavlos Panteliadis, Tiphaine Delaunay, Ernie Weijers, Jordy Vercauteren, Ronald Hoogerbrugge, Marieke Dijkema, Paul S. Monks and Edward Roekens 264, 
PM2.5 Source Apportionment in China Mei Zheng, Caiqing Yan and Xiaoying Li, 293, 
Case Studies of Source Apportionment from the Indian Sub-continent Mukesh Khare and Isha Khanna, 315, 
Health Effects of Airborne Particles in Relation to Composition, Size and Source Frank J. Kelly and Julia C. Fussell, 344, 
Subject Index, 383, 

CHAPTER 1

Emissions of Primary Particulate Matter

M. GUEVARA

ABSTRACT

Particulate matter (PM) accounts for a complex group of air pollutants with properties and impacts that vary according to its composition and size. The emission rates, size and composition of primary PM emissions are challenging to determine since they depend not only on the sector considered, but also on the fuel properties, technology and other characteristics of the emission process. At the European level, fine carbonaceous particles are generally the dominant components of primary PM emissions, the most important sources of organic and black carbon being residential biomass combustion and diesel vehicle engines, respectively. On the other hand, soil particles generated by wind erosion processes, traffic resuspension, mining and construction operations, and agricultural land management activities are large contributors to the coarse fraction of primary PM emissions. European PM emissions are decreasing as a result of implemented EU legislation mainly focused on road transport and large point sources. Nevertheless, emissions released by residential solid fuel appliances have been increasing due to a lack of regulations, a tendency that is expected to change with the eco-design directive. The decrease of traffic PM exhaust emissions has also increased the importance of traffic non-exhaust emissions, a major source of metals in urban areas.

1 Introduction

Particulate matter (PM) is a generic term used to describe a mixture of solid particles and liquid droplets (aerosols) that vary in size and composition, depending on the location and time (Table 1).

PM is made up of a large number of components, including elemental or black carbon (BC) and organic carbon (OC) compounds, sulfate (SO4-2), nitrate (NO3-), trace metals, crustal material (i.e. soil particles) and sea salt. PM also comes in a wide range of sizes and includes PM with diameter less than or equal to 10 µm (PM10), PM with diameter less than or equal to 2.5 µm (PM2.5), also denoted as fine particles, PM with diameter less than or equal to 0.1 pm (PM), also denoted as ultrafine particles (UFP), and PM with diameter less than or equal to 0.05 µm (PM0.05), also denoted as nanoparticles.

In terms of source of origin, PM can be directly emitted from anthropogenic (man-made) or natural sources (i.e. primary PM), or formed in the atmosphere from a series of gaseous combustion by-products such as volatile organic compounds (VOCs), ammonia (NH3), oxides of sulfur (SOx) and oxides of nitrogen (NOx) (i.e. secondary PM). Primary PM originates predominantly from combustion (e.g. vehicle engines) and high-temperature processes (e.g. smelting and welding industrial operations), as well as from mechanical disruption processes and man- or wind-induced events causing suspension of particles (e.g. traffic resuspension of street dust). On the other hand, secondary PM is formed by gas-to-particle conversion in the atmosphere and/or condensation of gaseous compounds on pre-existing aerosol particles, mainly involving NOx, SOx, NH3 and VOCs, which may react with O3, •OH and other reactive molecules forming secondary inorganic aerosols (SIA) and secondary organic aerosols (SOA).

Unlike other pollutants, such as SO2 or NH3, PM describes a complex group of air pollutants with properties and impacts that vary according to their composition and size. For instance, BC is linked to a range of climate impacts (e.g. increased temperatures) owing to its capability of directly absorbing light, reducing the albedo of snow and ice and interacting with clouds. On the other hand, several European cohort studies have reported that short- and long-term exposure to PM2.5 is associated with a number of health risks, such as lung cancer. The results of these studies have formed the basis for the International Research Agency on Cancer (IARC) to classify PM as carcinogenic to human beings (Group 1).

The main objective of the present chapter is to describe and analyse the main factors that characterize European primary PM emissions, including: main sources of origin, size distribution and chemical composition (speciation), current emission inventories, trends and regulations, and mitigation measures. Despite having a significant contribution to ambient particle concentrations, secondary PM is not considered in the present chapter. The complexity of the atmospheric aerosol processes and other factors (e.g. precursor gases) influencing its formation suggest the need for treating it separately in a more extensive study.

Section 2 of this chapter lists and describes the main anthropogenic and natural emission sources that contribute to total PM emissions in Europe. In Sections 3 and 4 a thorough analysis of the size distribution and speciation of PM emissions is conducted, respectively. Section 5 describes the main European PM emission inventories currently used, while Section 6 performs an analysis of PM trends in Europe. Finally, Section 7 focuses on current regulations and mitigation measures that affect PM emissions.

2 Source Categories

Primary PM is derived from a wide range of sources (both natural and anthropogenic), the contribution of each one varying with the location, season and time of day (Figure 1).

This section introduces and describes the sources that currently present the most significant contributions to European PM emissions.

2.1 Residential Combustion

Recently, interest has grown in biomass combustion as an environmentally friendly way of heating homes whilst at the same time reducing climate change impact and contributing to energy security. In this sense, the use of wood and other biomass in residential small combustion installations has been enhanced by several greenhouse gas strategies and targets for renewable energy. For instance, in 2014 the United Kingdom introduced the Domestic Renewable Heat Incentive (RHI), a financial support programme for renewable heat that offers payments to households for the installation of biomass heating systems to provide central heating and hot water. Moreover, the increase during the economic crisis of other fuel prices typically used in the residential sector (e.g. fuel oil) also triggered the use of biomass, which is less expensive, especially in those countries more affected by the recession, such as Greece.

Despite being labelled as a renewable fuel that can contribute to mitigating climate change, the combustion of biomass in small heating combustion installations is currently a major source of primary PM emissions, especially in wintertime. In 2013, emissions released from small residential combustion appliances were reported as the largest source of PM10 (38%) and PM2.5 (52%) in the EU-28 region. The high contribution of residential wood combustion (RWC) is mainly owing to the fact that: (i) burning conditions are often inefficient (i.e. low combustion temperatures, which leads to incomplete combustion) and (ii) household appliances used for the combustion of biomass usually lack emission controls or regulations.

In each European country, the contribution of RWC towards the total PM10 and PM2.5 emissions varies depending on its energy balance (i.e. relative amount of biomass consumed at the residential level with respect to other fuels) and the type of appliances used and fuels burned. The amount of appliances (e.g. fireplace, woodstove, pellet stove, pellet boilers) and biofuels (e.g. cork oak, pine, olive pit) used for RWC is very large and their use varies from one country to another. A survey conducted in Portugal reported that the main appliances used for RWC in the country are fireplaces (43%) and woodstoves or traditional ovens (24%). On the other hand, in Finland the biggest portion of wood is burnt in masonry heaters and ovens (38%), log boilers (24%) and sauna stoves (15%), with fireplaces representing only 5% of the total combustion installations used. Masonry heaters and ovens have qualities that allow better burning conditions, higher efficiency and subsequently lower PM emissions than conventional fireplaces. While in 2013 the amount of biomass used in the residential sector was 62% higher in Finland than in Portugal, the amount of Finish PM2.5 emissions reported for the same year and sector was just 28% larger than in Portugal.

Several studies have shown that the amount of PM emitted varies widely with category of burning appliance and biomass type. One of the most recent studies focusing on this topic was developed under the framework of the AIRUSE LIFE project. Emissions from different biofuels and appliances (those most prevalent in southern Europe) were analysed to obtain a detailed characterisation of emission profiles resulting from RWC. Results from this and previous studies shown that open fireplaces are the appliances that present the highest particulate emission factors (EFs; amount of pollutant emitted per activity unit) owing to low temperatures, which contribute to inefficient combustion. Compared to modern eco-labelled woodstove, PM2.5 EF from traditional fireplaces can be up to 10-50 times higher. Variations in the PM emissions can also be found within the same type of appliance owing to the operation conditions (e.g. air-staging settings and the thermal load). On the other hand, the highest EF are observed for biomass fuels other than pellets (e.g. olive pit, shell of pine, nuts, almond shell), the variations being related to the different ash contents of the fuels.

Apart from fuel parameters and operation conditions, the measurement protocol applied is another important factor that influences the variation of EF for the same appliance type. A detailed survey and review of the various RWC EF in use in Europe concluded that the most important type of measurement techniques are filter measurements, which measure only solid particles, and dilution tunnel measurements, which measure solid particles and condensates of semi-volatile organics. The EF compiled by the study presented a high variation as a function of the technique used. For instance, EF for conventional wood stoves obtained with filter measurement ranged from 64 to 87 mg MJ-1, while measurements in dilution tunnels showed results in the range from 340 to 544 mg MJ-1. The choice to use a filter measurement- or dilution tunnel measurement-based EF can have a great impact when estimating PM RWC emissions and analysing the contribution of this source to primary organic aerosols (POA).

2.2 Road Transport

Road transport is one of the main sources of PM in urban areas. In 2013, road transport alone was responsible for 12% and 13% of total primary PM10 and PM2.5 emissions in the EU-28 region, respectively. Nevertheless, at the city level these contributions can go up to 40–50%, thus constituting the main urban emission source.

PM emissions from traffic are categorised according to the mode of formation. The combustion of fuels, mainly gasoline and diesel, in internal combustion engines (exhaust emissions) is generally assumed as the principal mechanism by which PM is formed. On the other hand, road transport also involves the interactions between vehicles and the road surface and the use of brakes, which can result in the release of PM emissions. This category of emissions is known as non-exhaust emissions and includes: (i) tyre wear, (ii) brake wear, (iii) road surface wear and (iv) resuspension. The first three sources involve mechanical abrasion, grinding, crushing and corrosion processes, while the last one refers to the resuspension of the dust collected on the road surface owing to vehicle-generated turbulence.

The quantification of exhaust traffic emissions mainly depends on the engine type, engine age (i.e. Euro categories set up by European legislation), after-treatment technology, fuel properties (e.g. fuel sulfur content), level of maintenance of the vehicle, environmental conditions and driving conditions. Exhaust emission rates from vehicles can be estimated from controlled conditions in laboratories (i.e. engine and chassis dynamometer studies) or real-world conditions (i.e. tunnel, remote sensing, on-road and onboard measurements). The use of both approaches indicates that in general PM emission rates from diesel vehicles are significantly higher compared to those from gasoline ones, and that Heavy Duty Diesel Vehicles (HDDVs) are the highest emitters among the different diesel vehicle categories. However, increasingly restrictive European diesel emission standards (Section 7) have resulted in a clear reduction of diesel PM emission levels by about 80-90%. In some cases vehicles equipped with diesel particle filters (DPF) (part of Euro 4 and all from Euro 5 and on) even show lower PM levels than gasoline vehicles. The effect of speed on PM exhaust emissions is also increasingly reduced with the introduction of new Euro standards. Generally speaking, low-speed operations lead to higher emission rates. Nevertheless, and as shown by the two reference vehicle emission models in Europe (COPERT; Computer Programme to calculate Emissions from Road Transport and HBEFA; Handbook of Emission Factors), the shape of emission rates vs. speed curves is flatter for the new emission standards than the old ones. On the other hand, PM emission rates significantly increase during acceleration as well as with aggressive driving or heavy load conditions.

Non-exhaust emissions are more difficult to quantify than exhaust emissions owing to the strong influence of not only the type of vehicle and traffic conditions, but also the material properties (e.g. tyre type, road pavement, grain size) and meteorological factors (e.g. temperature, road wetness). Non-exhaust particles derived from resuspension processes seem dominant in terms of mass, although this can vary from one country to another owing to the effect of humidity, the use of studded tyres and the contribution from road sanding. Resuspension PM10 emission rates estimated by roadside measurements on inner-city urban roads across Europe present a wide variation: UK (14-23 mg VKT-1), Germany (57-109 mg VKT-1), Denmark (46-108 mg VKT-1), Finland (121 mg VKT-1), Sweden (198 mg VKT-1). Several campaigns have pointed out a strong correlation between HDDVs and resuspension, the emission rate for this class of vehicle being up to 20 times higher than that for passenger cars. Resuspension emissions in motorways tend to be lower than those in other types of roads (especially urban streets) since higher average vehicle speeds and traffic intensity lead to a lower on-road dust reservoir. The large variation in the resuspension emission rates make them applicable only to the site of study or areas with similar characteristics. During recent years, different numerical approaches have been developed with the intention of reducing the dependency of non-exhaust emission quantification on local measurements. One of the most recent models, the NORTRIP model, is capable of estimating non-exhaust traffic PM emissions based on the impact of surface wetness, the buildup of dust on the road surface, the surface moisture and the effects of applying traction maintenance measures (e.g. salting and sanding).

Several studies across Europe have pointed out that the contribution of non-exhaust emissions to PM10 can be comparable or even higher than that of exhaust emissions, especially in Scandinavian and Mediterranean countries, owing to studded tyres and road sanding in the former and drier climates in the latter. The contribution of non-exhaust emissions to total PM10 in urban areas is expected to grow during the coming years up to approximately 80–90% by 2020. This increase is the result of a combination of several actions that are currently in place to reduce PM emissions from motor exhausts (both at legislative and technological levels) and a lack of abatement measures for non-exhaust emissions.

2.3 Energy and Manufacturing Industries

Emissions from energy (power plants and refineries) and manufacturing industries represent the second-largest source of primary PM10 (28%) and PM2.5 (21%) in the EU-28 region. However, and with the exception of certain cities close to industrial environments, the contributions of these activities to primary PM in urban areas is less pronounced than that of road transport (around 10%).

There are three main mechanisms by which industrial PM is formed. The first involves fuel combustion processes (e.g. coal, oil, coke) in conventional boilers, furnaces, gas turbines, reciprocating engines or other combustion devices. PM emissions can also arise from non-combustion processes, such as mechanical treatments of raw materials (non-metallic industries) or casting operations (iron and steel industries). Emissions derived from both combustion and non-combustion processes are usually channelled through ducts (i.e. stacks), which makes them more controllable. Finally, industrial PM emissions can also occur during the handling, transport and storage of dusty raw materials (e.g. clinker, cement). These emissions, referred to as "diffuse", are more complicated to quantify and control than the channeled ones, owing to the difficulties in determining their flux and location of occurrence inside the industrial areas.

(Continues...)

Excerpted from Airborne Particulate Matter by R.E. Hester, R. M. Harrison, X. Querol. Copyright © 2016 The Royal Society of Chemistry. Excerpted by permission of The Royal Society of Chemistry.
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Edition details

• Publisher: Royal Society of Chemistry
• Publication date: 2016
• ISBN 10: 1782624910
• ISBN 13: 9781782624912
• Binding: Hardcover
• Language: English
• Edition number: 1
• Number of pages: 405
• Editor: Harrison R M, Hester R E, Querol Xavier