Publications by authors named "Jean-Philippe Putaud"

Carbonaceous aerosols (CA), composed of black carbon (BC) and organic matter (OM), significantly impact the climate. Light absorption properties of CA, particularly of BC and brown carbon (BrC), are crucial due to their contribution to global and regional warming. We present the absorption properties of BC (b) and BrC (b) inferred using Aethalometer data from 44 European sites covering different environments (traffic (TR), urban (UB), suburban (SUB), regional background (RB) and mountain (M)).

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There is a body of evidence that ultrafine particles (UFP, those with diameters ≤ 100 nm) might have significant impacts on health. Accordingly, identifying sources of UFP is essential to develop abatement policies. This study focuses on urban Europe, and aims at identifying sources and quantifying their contributions to particle number size distribution (PNSD) using receptor modelling (Positive Matrix Factorization, PMF), and evaluating long-term trends of these source contributions using the non-parametric Theil-Sen's method.

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Article Synopsis
  • Atmospheric new particle formation (NPF) is the natural process of creating tiny particles (sub-10 nm) from gases, observed globally in various environments.
  • Although these particles impact total and ultrafine particle concentrations, there is limited research on their health effects largely due to a lack of specific identifiers in existing data.
  • This study introduces an automated machine learning algorithm that identifies NPF events from particle data across 65 global measurement sites from 1996 to 2023, facilitating future research on NPF.
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Ultrafine particles (UFP, those with diameters ≤ 100 nm), have been reported to potentially penetrate deeply into the respiratory system, translocate through the alveoli, and affect various organs, potentially correlating with increased mortality. The aim of this study is to assess long-term trends (5-11 years) in mostly urban UFP concentrations based on measurements of particle number size distributions (PNSD). Additionally, concentrations of other pollutants and meteorological variables were evaluated to support the interpretations.

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Article Synopsis
  • This study focuses on how to accurately measure equivalent black carbon (eBC) concentrations using filter absorption photometers (FAPs) by understanding the mass absorption cross-section (MAC).
  • Researchers analyzed data from 22 different sites to compare various methods for calculating MAC, leading to different classifications of eBC such as LeBC, MeBC, and ReBC, with significant differences observed in measurement outcomes.
  • Results showed that MAC varies by site and season, influencing the observed trends in elemental carbon (EC), revealing a need for careful MAC consideration when interpreting eBC data to reduce uncertainty in measurements.
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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 (SUB, n = 4), and regional background (RB, n = 1) monitoring sites in Europe (25) and USA (1). Briefly, the spatial-temporal distribution characteristics of the deposition of LDSA, including diel, weekly, and seasonal patterns, were analyzed. Then, the relationship between LDSA and other air quality metrics at each monitoring site was investigated.

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Article Synopsis
  • This study examined variations in equivalent black carbon (eBC) levels across urban Europe to assess its potential as a key air quality indicator, collecting data from various measurement stations from 2006 to 2022.
  • The findings emphasized the necessity for standardization in eBC measurements for better comparisons, revealing a decreasing trend in eBC levels from traffic zones to suburban and regional areas, with Southern cities generally having higher concentrations than those in the North.
  • Additionally, fossil fuel combustion, particularly from traffic, was identified as the primary source of eBC, and while there was an overall decreasing trend in eBC levels over the decade, some cities showed stable or slightly rising concentrations.
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Article Synopsis
  • The study analyzed hourly particle number size distributions (PNSD) from 26 European sites and 1 in the US to understand urban ultrafine particles and their air quality impacts.
  • Findings show that particle number concentrations (PNC) are highest in traffic areas compared to urban background and suburban locations, with noticeable increases as one moves from Northern to Southern Europe.
  • Recommendations highlight the need for specific PNSD monitoring to accurately assess the health effects of nanoparticles, with calls for standardized measurement practices to ensure comparability across different sites.
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Airborne particulate matter (PM) is a pollutant of concern not only because of its adverse effects on human health but also on visibility and the radiative budget of the atmosphere. PM can be considered as a sum of solid/liquid species covering a wide range of particle sizes with diverse chemical composition. Organic aerosols may be emitted (primary organic aerosols, POA), or formed in the atmosphere following reaction of volatile organic compounds (secondary organic aerosols, SOA), but some of these compounds may partition between the gas and aerosol phases depending upon ambient conditions.

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The European Committee for Standardisation (CEN) Technical Committee 264 'Air Quality' has recently produced a standard method for the measurements of organic carbon and elemental carbon in PM within its working group 35 in response to the requirements of European Directive 2008/50/EC. It is expected that this method will be used in future by all Member States making measurements of the carbonaceous content of PM. This paper details the results of a laboratory and field measurement campaign and the statistical analysis performed to validate the standard method, assess its uncertainty and define its working range to provide clarity and confidence in the underpinning science for future users of the method.

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European Committee for Standardisation (CEN) Technical Committee 264 'Air Quality' has recently produced a standard method for the measurements of anions and cations in PM within its Working Group 34 in response to the requirements of European Directive 2008/50/EC. It is expected that this method will be used in future by all Member States making measurements of the ionic content of PM. This paper details the results of a field measurement campaign and the statistical analysis performed to validate this method, assess its uncertainty and define its working range to provide clarity and confidence in the underpinning science for future users of the method.

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Marine aerosol contributes significantly to the global aerosol load and consequently has an important impact on both the Earth's albedo and climate. So far, much of the focus on marine aerosol has centred on the production of aerosol from sea-salt and non-sea-salt sulphates. Recent field experiments, however, have shown that known aerosol production processes for inorganic species cannot account for the entire aerosol mass that occurs in submicrometre sizes.

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