Xavier Querol

Spanish National Research Council, in Barcelona, Spain · Institute of Environmental Assessment and Water Research, Department of Geosciences, Barcelona, Spain

The Absorption Angstrom Exponent (AAE) is an optical parameter that describes the spectral dependence of light absorption by aerosols. It is intensively employed for black carbon (BC) source apportionment and aerosol characterization (e.g., BC, Brown Carbon “BrC”, and dust). AAE has been widely investigated using data from filter-absorption photome...

Organic aerosols (OA) have recently been shown to be the dominant contributor to the oxidative potential of airborne particulate matter in northeastern Spain. We collected PM10 filter samples every fourth day from January 2017 to March 2018 at two sampling stations located in Barcelona city and Montseny Natural Park, representing urban and rural ar...

Tropospheric ozone threatens human health and crop yields, exacerbates global warming, and fundamentally changes atmospheric chemistry. Evidence has pointed toward widespread ozone increases in the tropo-sphere, and particularly surface ozone is chemically complex and difficult to abate. Despite past successes in some regions, a solution to new cha...

In highly industrialized areas, abating particulate matter (PM) is complex owing to the variety of emission sources with different chemical profiles that may mix in the atmosphere. Gijón-an industrial city in northern Spain-was selected as a case study to better understand the key emission sources and improve air quality in highly industrialized ar...

The Mediterranean is a crossroad region for different air masses and, therefore, of many contrasted aerosol types. It has been a natural laboratory to study their long-range transport, the formation of secondary particles from gaseous precursors, the effects of aerosols on the local and regional radiation budgets, and their consequences on air qual...

Tropospheric ozone (O3) is a secondary air pollutant that affects human health, vegetation and climate, especially in Mediterranean countries such as Spain. In order to tackle this long-standing issue, the Spanish government recently started to design the Spanish O3 Mitigation Plan. To support this initiative and ultimately provide recommendations,...

This study aims to picture the phenomenology of urban ambient total lung deposited surface area (LDSA) (including head/throat (HA), tracheobronchial (TB), and alveolar (ALV) regions) based on multiple path particle dosimetry (MPPD) model during 2017-2019 period collected from urban background (UB, n = 15), traffic (TR, n = 6), suburban background (...

Source apportionment (SA) for indoor air pollution is challenging due to the multiplicity and high variability of indoor sources, the complex physical and chemical processes that act as primary sources, sinks and sources of precursors that lead to secondary formation, and the interconnection with the outdoor environment. While the major indoor sour...

This study analyzed the variability of equivalent black carbon (eBC) mass concentrations and their sources in urban Europe to provide insights into the use of eBC as an advanced air quality (AQ) parameter for AQ standards. This study compiled eBC mass concentration datasets covering the period between 2006 to 2022 from 50 measurement stations, incl...

The particle size distribution (PSD) of mineral dust has a strong effect on the impacts of dust on climate. However, our understanding of the emitted dust PSD, including its variability and the fraction of super-coarse dust (diameter >10 µm), remains limited. Here, we provide new insights into the size-resolved dust emission process based on a fiel...

Detailed knowledge on the formation of new aerosol particles in the atmosphere from precursor gases, and their subsequent growth, commonly known as new particle formation (NPF) events, is one of the largest challenges in atmospheric aerosol science. High pre-existing particle loadings are expected to suppress the formation of new atmospheric aeroso...

INDAIRPOLLNET (INDoor AIR POLLution NETwork https://indairpollnet.eu/) is a European COST Action network programme, running from September 2018 until March 2023. It has more than 200 indoor and outdoor air quality scientists from universities, large and small companies, and research institutes around Europe and beyond. Their expertise covers chemis...

The effect of mineral dust emitted from arid and semiarid surfaces upon climate and ecosystems depends fundamentally on their particle size distribution (PSD) and size-resolved mineralogical composition. However, soil mineralogy atlases used for mineral-speciated dust modelling are highly uncertain as they are derived extrapolating mineralogical an...

Source apportionment (SA) techniques allocate the measured ambient pollutants with their potential source origin; thus, they are a powerful tool for designing air pollution mitigation strategies. Positive Matrix Factorization (PMF) is one of the most widely used SA approaches, and its multi-time resolution (MTR) methodology, which enables mixing di...

Aerosols are one of the most important pollutants in the atmosphere and have been monitored for the past few decades by both remote sensing and in situ observation platforms to assess the effectiveness of government-managed reduction emission policies and assess their impact on the radiative budget of the Earth's atmosphere. In fact, aerosols can d...

This study aims to support the development of Spain’s Ozone Mitigation Plan by evaluating the present-day spatial variation (2015–2019) and trends (2008–2019) for seven ground-level ozone (O3) metrics relevant for human/ecosystems exposure and regulatory purposes. Results indicate that the spatial variation of O3 depends on the part of the O3 dist...

Among the aerosol particles optical properties, the Absorption Angstrom Exponent (AAE) is a crucial parameter describing the spectral dependence of light absorption by aerosols. It is intensively employed for black carbon (BC) source apportionment and aerosol characterization (e.g., BC, Brown Carbon "BrC," and dust). AAE has been widely investigate...

The chemical and morphological properties of mineral dust aerosols emitted by wind erosion from arid and semi-arid regions influence climate, ocean, and land ecosystems; air quality; and multiple socio-economic sectors. However, there is an incomplete understanding of the emitted dust particle size distribution (PSD) in terms of its constituent min...

Desert dust and sandstorms are recurring environmental phenomena that are reported to produce serious health risks worldwide. This scoping review was conducted to identify the most likely health effects of desert dust and sandstorms and the methods used to characterize desert dust exposure from the existing epidemiological literature. We systematic...

This is an account that should be heard of an important struggle: the struggle of a large group of experts who came together at the beginning of the Covid-19 pandemic to warn the world about the risk of airborne transmission and the consequences of ignoring it. We alerted the World Health Organization (WHO) about the potential significance of the a...

The 2017–2019 hourly particle number size distributions (PNSD) from 26 sites in Europe and 1 in the US were evaluated focusing on 16 urban background (UB) and 6 traffic (TR) sites in the framework of Research Infrastructures services reinforcing air quality monitoring capacities in European URBAN & industrial areaS (RI-URBANS) project. The main obj...

Research on coal-hosted strategic metal ore deposits is an important subject in coal geology and mineral deposit worldwide. However, the related geological characteristics of coals from Vietnam have seldom been investigated, let alone the strategic metals in coals. This paper investigates the mineralogical and geochemical characteristics of the Upp...

Mineral dust effects upon climate are strongly affected by its particle size distribution (PSD). In particular, the emitted dust PSD partly controls the dust lifetime and its global distribution. Despite the extensive research performed on this topic over the last decades, there are still substantial gaps in our understanding of the emitted PSD alo...

Despite international efforts to limit worker exposure to coal dust, it continues to impact the health of thousands of miners across Europe. Airborne coal dust has been studied to improve risk models and its control to protect workers. Particle size distribution analyses shows that using spraying systems to suppress airborne dusts can reduce partic...

The chemical and morphological properties of mineral dust aerosols emitted by wind erosion from arid and semi-arid regions influence climate, ocean and land ecosystems, air quality, and multiple socio-economic sectors. However, there is an incomplete understanding of the emitted dust particle size distribution (PSD) in terms of its constituent mine...

Aluminium is the most common substrate in studies using impactors for the measurement of the number or the weight of size-segregated atmospheric particulate matter (PM), as its characteristics perfectly fit impactor requirements. However, its use is not recommended by manufacturers when one of the purposes of the study is the determination of the m...

This study provides an up-to-date assessment of the present-day spatial distribution (2015–2019) and trends (2008–2019) in Spain for eight ozone (O3) metrics relevant for human/ecosystems exposure and regulatory purposes. Main O3 precursors were also analyzed using ground-level observations, satellite observations and emission inventories. The pres...

According to the urgent need to substantially reduce air pollution across the EU and reduce the associated health impacts, it is critical to develop observations of aerosol properties in European cities, which will serve for more effective air quality monitoring strategies in the 2030 horizon timeline. In this regard, the RI-URBAN project (Fig. 1)...

This paper represents the first integrated research on the mineralogical, geochemical and stable isotope characteristics of the Upper Triassic high‑sulfur coals from the Khanh Hoa open-pit mine, Thai Nguyen Coalfield, NE Vietnam. Formed in a marine-influenced carbonate succession, the Khanh Hoa coal is characterized by medium ash yield, low volatil...

A sampling methodology and a mathematical data treatment were developed that enable to determine not only total suspended particulates (TSP) emitted at channeled sources but also the PM10, PM2.5, and PM1 mass fractions (w10, w2.5, and w1) and emission factors (E.F.), using a seven-stage cascade impactor. Moreover, a chemical analysis was performed...

The anomalous enrichment of the rare earth elements and yttrium (REY), U, Mo, As, Se, and V in the coal-bearing intervals intercalated within the carbonate successions in South China has attracted much attention due to the highly promising recovery potential for these elements. This study investigates the mineralogical and geochemical characteristi...

The RI-URBAN project focuses on human exposure to outdoor ambient ultrafine (UFP) particles and particulate matter (PM) concentrations with special attention paid to the role that the sources of these atmospheric constituents have on human health. One specific objective is to interpret and reveal the benefit of obtaining datasets from urban sites o...

Black carbon (BC) is recognized as the most important warming agent among atmospheric aerosol particles. The absorption efficiency of pure BC is rather well-known, nevertheless the mixing of BC with other aerosol particles can enhance the BC light absorption efficiency, thus directly affecting Earth's radiative balance. The effects on climate of th...

The aim of the "Sand and Dust Storms Compendium: Information and Guidance on Assessing and Addressing the Risks" is to provide information and guidance on how to assess and address the risks posed by sand and dust storms and plan actions to combat sand and dust storms. The Compendium brings together information and guidance from a wide range of sou...

PM10 was collected during an EMEP winter campaign of 2017–2018 in two urban background sites in Barcelona (BCN) and Granada (GRA), two Mediterranean cities in the coast and inland, respectively. The concentrations of PM10, organic carbon (OC), elemental carbon (EC), and organic molecular tracer compounds such as hopanes, anhydro-saccharides, polycy...

Oxidative potential (OP) is considered to be an efficient indicator of particulate matter (PM) to induce oxidative stress in the lungs and is increasingly considered to be a relevant health metric. In this study, two complementary OP assays were deployed, including dithiothreitol (DTT) and ascorbic acid (AA) assays, to investigate the potential tox...

This paper reports on the chemical speciation and leaching behavior of a selected group of hazardous trace pollutants in lignite and lignite-petcoke blend co-combustion products from three power stations in China. The evaluation of speciation results showed that, during combustion, oxidizable elements, mainly As and Mo, bound to organic matter and...

In this study, global reanalysis dataset fields of meteorological parameters (temperature and geopotential height at different atmospheric levels) in the period 1948–2020, were used to characterize the main dynamic and thermodynamic features of African dust outbreaks (ADO) produced over regions of the Iberian Peninsula and the Balearic Islands. The...

Black carbon (BC) is recognized as the most important warming agent among atmospheric aerosol particles. The absorption efficiency of pure BC is rather well known, nevertheless the mixing of BC with other aerosol particles can enhance the BC light absorption efficiency, thus directly affecting the Earth radiative balance. The effects on climate of...

The current study investigates the mineralogical and geochemical characteristics of the Late Triassic coals from the Coc Sau open-pit mine, Cam Pha Coalfield (Quang Ninh Province, Northeastern Vietnam) using Powder X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), inductively coupled plasma atomic-emission spectrometry...

The 2017-2019 hourly particle number size distributions (PNSD) from 26 sites in Europe and 1 in the US were evaluated focusing on 16 urban background (UB) and 6 traffic (TR) sites in the framework of Research Infrastructures services reinforcing air quality monitoring capacities in European URBAN & industrial areaS (RI-URBANS) project. The main obj...

Atmospheric particulate matter (PM) is a priority pollutant for urban air pollution management because of its negative effects on human health and visibility. Emissions from road traffic have been a major focus of management over the past few decades, but non-exhaust emissions i.e., emissions from brake, tyre, road wear, and the resuspension of dus...

Background The recent evidence of the short-term impact of air pollution on youth cognitive functions is based primarily on observational studies. Objectives We conducted a randomized controlled trial to assess whether purifying the air of the classrooms produced short-term changes in attention processes of adolescents. Methods We recruited a tot...

Measurements of CO2 and counting of occupants were carried out in 37 public bus trips during commuting rush hours in Barcelona (NE Spain) with the aim of evaluating parameters governing ventilation inside the vehicles and proposing actions to improve it. The results show that CO2 concentrations (1039 and 934 ± 386 ppm, as average and median, during...

Background The evidence on the association between ultrafine (UFP) particles and mortality is still inconsistent. Moreover, health effects of specific UFP sources have not been explored. We assessed the impact of UFP sources on daily mortality in Barcelona, Helsinki, London, and Zurich. Methods UFP sources were previously identified and quantified...

Providing reliable observations of aerosol particles' absorption properties at spatial and temporal resolutions suited to climate models is of utter importance to better understand the effects that atmospheric particles have on climate. Nowadays, one of the instruments most widely used in international monitoring networks for in situ surface measur...

Public bus system worldwide transports daily more than 34 million people; therefore, air quality inside buses is an important urban air pollution issue. Airborne microbiological composition and abundance was examined inside five different fuel type buses (diesel (EURO IV and EURO V), hybrid diesel (HD), compressed natural gas (CNG), hybrid natural...

New particle formation (NPF) events occur almost everywhere in the world and can play an important role as a particle source. The frequency and characteristics of NPF events vary spatially, and this variability is yet to be fully understood. In the present study, long-term particle size distribution datasets (minimum of 3 years) from 13 sites of va...

This study evaluates geochemical and oxidative potential (OP) properties of the respirable (finer than 4 μm) fractions of 22 powdered coal samples from channel profiles (CP4) in Chinese mined coals. The CP4 fractions extracted from milled samples of 22 different coals were mineralogically and geochemically analysed and the relationships with the OP...

The preventive and cautionary measures taken by the UAE and Abu Dhabi governments to reduce the spread of the coronavirus disease (COVID-19) and promote social distancing have led to a reduction of mobility and a modification of economic and social activities. This paper provides statistical analysis of the air quality data monitored by the Environ...

Severe episodic air pollution blankets entire cities and regions and have a profound impact on humans and their activities. We compiled daily fine particle (PM 2.5) data from 100 cities in five continents, investigated the trends of number, frequency, and duration of pollution episodes, and compared these with the baseline trend in air pollution. W...

In this work, time-series analyses of the chemical composition and source contributions of PM2.5 from an urban background station in Barcelona (BCN) and a rural background station in Montseny (MSY) in northeastern Spain from 2009 to 2018 were investigated and compared. A multisite positive matrix factorization analysis was used to compare the sourc...

The evolution of fine aerosol (PM1) species as well as the contribution of potential sources to the total organic aerosol (OA) at an urban background site in Barcelona, in the western Mediterranean basin (WMB) was investigated. For this purpose, a quadrupole aerosol chemical speciation monitor (Q-ACSM) was deployed to acquire real-time measurements...

Looking further than COVID-19, some of the key messages: 1. We from now on should include the risk of indoor respiratory infections in our design of buildings and its ventilation. 2. Treat the air quality in a similar way as we are used to for water and food quality. 3. ‘Visualize’ the air quality by displaying monitoring values (e.g. CO2 concentra...

PurposeThe aim of the present study was to investigate the effect of short-term exposure to ambient black carbon (BC) on daily cause-specific mortality, including mortality due to respiratory, cardiovascular, ischemic heart and cerebrovascular diseases in Tehran, Iran.Materials and methodsDaily non-accidental death counts, meteorological data and h...

The behaviour and speciation of inorganic trace pollutants were studied in a 270 MWh coal-fired power station equipped with denitrification (DeNOx)-based selective catalytic reduction (SCR), electrostatic precipitators (ESP) and ammonia flue gas desulphurisation (NH3-FGD) controls. The aqueous (NH4)2SO4 slurry (pH 3.2) showed remarkably high concen...