Cardiopulmonary Mortality and Fine Particulate Air Pollution by Species and Source in a National U.S. Cohort

The purpose of this study was to estimate cardiopulmonary mortality associations for long-term exposure to PM2.5 species and sources (i.e., components) within the U.S. National Health Interview Survey cohort. Exposures were estimated through a chemical transport model for six species (i.e., elemental carbon (EC), primary organic aerosols (POA), secondary organic aerosols (SOA), sulfate (SO4), ammonium (NH4), nitrate (NO3)) and five sources of PM2.5 (i.e., vehicles, electricity-generating units (EGU), non-EGU industrial sources, biogenic sources (bio), “other” sources). In single-pollutant models, we found positive, significant (p < 0.05) mortality associations for all components, except POA. After adjusting for remaining PM2.5 (total PM2.5 minus component), we found significant mortality associations for EC (hazard ratio (HR) = 1.36; 95% CI [1.12, 1.64]), SOA (HR = 1.11; 95% CI [1.05, 1.17]), and vehicle sources (HR = 1.06; 95% CI [1.03, 1.10]). HRs for EC, SOA, and vehicle sources were significantly larger in comparison to those for remaining PM2.5 (per unit μg/m3). Our findings suggest that cardiopulmonary mortality associations vary by species and source, with evidence that EC, SOA, and vehicle sources are important contributors to the PM2.5 mortality relationship. With further validation, these findings could facilitate targeted pollution regulations that more efficiently reduce air pollution mortality.This publication was developed as part of the Center for Air, Climate, and Energy Solutions (CACES), which was supported under Assistance Agreement No. R835873 awarded by the U.S. Environmental Protection Agency. It has not been formally reviewed by EPA. The views expressed in this document are solely those of authors and do not necessarily reflect those of the Agency. EPA does not endorse any products or commercial services mentioned in this publication. We also acknowledge support from the European Union’s Horizon 2020 Research and Innovation project REMEDIA under grant agreement No 874753.Peer Reviewed"Article signat per 13 autors/es:" Zachari A. Pond, Carlos S. Hernandez, Peter J. Adams, Spyros N. Pandis, George R. Garcia, Allen L. Robinson, Julian D. Marshall, Richard Burnett, Ksakousti Skyllakou, Pablo Garcia Rivera, Eleni Karnezi, Carver J. Coleman, C. Arden Pope III"Postprint (author's final draft

Organic aerosol in the summertime southeastern United States: components and their link to volatility distribution, oxidation state and hygroscopicity

The volatility distribution of the organic aerosol (OA) and its sources during the Southern Oxidant and Aerosol Study (SOAS; Centreville, Alabama) was constrained using measurements from an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and a thermodenuder (TD). Positive matrix factorization (PMF) analysis was applied on both the ambient and thermodenuded high-resolution mass spectra, leading to four factors: more oxidized oxygenated OA (MO-OOA), less oxidized oxygenated OA (LO-OOA), an isoprene epoxydiol (IEPOX)-related factor (isoprene-OA) and biomass burning OA (BBOA). BBOA had the highest mass fraction remaining (MFR) at 100 °C, followed by the isoprene-OA, and the LO-OOA. Surprisingly the MO-OOA evaporated the most in the TD. The estimated effective vaporization enthalpies assuming an evaporation coefficient equal to unity were 58 ± 13 kJ mol^(−1) for the LO-OOA, 89 ± 10 kJ mol^(−1) for the MO-OOA, 55 ± 11 kJ mol^(−1) for the BBOA, and 63 ± 15 kJ mol^(−1) for the isoprene-OA. The estimated volatility distribution of all factors covered a wide range including both semi-volatile and low-volatility components. BBOA had the lowest average volatility of all factors, even though it had the lowest O  :  C ratio among all factors. LO-OOA was the more volatile factor and its high MFR was due to its low enthalpy of vaporization according to the model. The isoprene-OA factor had intermediate volatility, quite higher than suggested by a few other studies. The analysis suggests that deducing the volatility of a factor only from its MFR could lead to erroneous conclusions. The oxygen content of the factors can be combined with their estimated volatility and hygroscopicity to provide a better view of their physical properties

Organic aerosol in the summertime southeastern United States: components and their link to volatility distribution, oxidation state and hygroscopicity

The volatility distribution of the organic aerosol (OA) and its sources during the Southern Oxidant and Aerosol Study (SOAS; Centreville, Alabama) was constrained using measurements from an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and a thermodenuder (TD). Positive matrix factorization (PMF) analysis was applied on both the ambient and thermodenuded high-resolution mass spectra, leading to four factors: more oxidized oxygenated OA (MO-OOA), less oxidized oxygenated OA (LO-OOA), an isoprene epoxydiol (IEPOX)-related factor (isoprene-OA) and biomass burning OA (BBOA). BBOA had the highest mass fraction remaining (MFR) at 100 °C, followed by the isoprene-OA, and the LO-OOA. Surprisingly the MO-OOA evaporated the most in the TD. The estimated effective vaporization enthalpies assuming an evaporation coefficient equal to unity were 58 ± 13 kJ mol^(−1) for the LO-OOA, 89 ± 10 kJ mol^(−1) for the MO-OOA, 55 ± 11 kJ mol^(−1) for the BBOA, and 63 ± 15 kJ mol^(−1) for the isoprene-OA. The estimated volatility distribution of all factors covered a wide range including both semi-volatile and low-volatility components. BBOA had the lowest average volatility of all factors, even though it had the lowest O  :  C ratio among all factors. LO-OOA was the more volatile factor and its high MFR was due to its low enthalpy of vaporization according to the model. The isoprene-OA factor had intermediate volatility, quite higher than suggested by a few other studies. The analysis suggests that deducing the volatility of a factor only from its MFR could lead to erroneous conclusions. The oxygen content of the factors can be combined with their estimated volatility and hygroscopicity to provide a better view of their physical properties

Volatility and Chemical Aging of Atmospheric Organic Aerosol

Organic particulate matter represents a significant fraction of sub-micrometer atmospheric aerosol mass. However, organic aerosol (OA) consists of thousands of different organic compounds making the simulation of its concentration, chemical evolution, physical and chemical properties extremely challenging. The identity of the great majority of these compounds remains unknown. The volatility of atmospheric OA is one of its most important physical properties since it determines the partitioning of these organic compounds between the gas and particulate phases. The use of lumped compounds with averaged properties is a promising solution for the representation of OA in atmospheric chemical transport models. The two-dimensional volatility basis set (2D-VBS) is a proposed method used to describe OA distribution as a function of the volatility and oxygen content of the corresponding compounds. In the first part of the work we evaluate our ability to measure the OA volatility distribution using a thermodenuder (TD). We use a new method combining forward modeling, introduction of ‘experimental’ error and inverse modeling with error minimization for the interpretation of TD measurements. The OA volatility distribution, its effective vaporization enthalpy, the mass accommodation coefficient and the corresponding uncertainty ranges are calculated. Our results indicate that existing TD-based approaches quite often cannot estimate reliably the OA volatility distribution, leading to large uncertainties, since there are many different combinations of the three properties that can lead to similar thermograms. We propose an improved experimental approach combining TD and isothermal dilution measurements. We evaluate this experimental approach using the same model and show that it is suitable for studies of OA volatility in the lab and the field. Measurements combining a thermodenuder (TD) and a High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) took place during summer and winter in Paris, France as part of the collaborative project MEGAPOLI and during the winter of 2013 in the city of Athens. The above volatility estimation method with the uncertainty estimation algorithm is applied to these datasets in order to estimate the volatility distribution for the organic aerosol (OA) and its components during the two campaigns. The concentrations of the OA components as a function of temperature were measured combining data from the thermodenuder and the aerosol mass spectrometer (AMS) with Positive Matrix Factorization (PMF) analysis. Combining the bulk average O:C ratios and volatility distributions of the various factors, our results are placed into the two-dimensional volatility basis set (2D-VBS) framework. The OA factors cover a broad spectrum of volatilities with no direct link between the average volatility and average O:C of the OA components. An intercomparison among the OA components of both campaigns and their physical properties is also presented. The approach combining thermodenuder and isothermal dilution measurements is tested in smog chamber experiments using OA produced during meat charbroiling. The OA mass fraction remaining is measured as a function of temperature in the TD and as a function of time in the isothermal dilution chamber. These two sets of measurements are used together to estimate the volatility distribution of the OA and its effective vaporization enthalpy and accommodation coefficient. In the isothermal dilution experiments approximately 20% of the OA evaporate within 15 min. In the TD almost all the OA evaporated at approximately 200oC. The resulting volatility distributions suggest that around 60-75% of the cooking OA (COA) at concentrations around 500 μg m-3 consists of low volatility organic compounds (LVOCs), 20-30% of semi-volatile organic compounds (SVOCs) and around 10% of intermediate volatility organic compounds (IVOCs). The estimated effective vaporization enthalpy of COA is 100 ± 20 kJ mol-1 and the effective accommodation coefficient is around 0.05. The characteristics of the COA factor from the Athens campaign are compared to those of the OA produced from meat charbroiling in these experiments. In the next step, different parameterizations of the organic aerosol (OA) formation and evolution in the two-dimensional Volatility Basis Set (2D-VBS) framework are evaluated using ground and airborne measurements collected in the 2012 Pan-European Gas AeroSOls-climate-interaction Study (PEGASOS) field campaign in the Po Valley, Italy. A number of chemical schemes are examined, taking into account various functionalization and fragmentation pathways for biogenic and anthropogenic OA components. Model predictions and measurements, both at the ground and aloft, indicate a relatively oxidized OA with little average diurnal variation. Total OA concentration and O:C ratios were reproduced within experimental error by a number of chemical aging schemes. Anthropogenic SOA is predicted to contribute 15-25% of the total OA, while SOA from intermediate volatility compounds oxidation another 20-35%. Biogenic SOA contributions varied from 15 to 45% depending on the modeling scheme. The average OA and O:C diurnal variation and their vertical profiles showed a surprisingly modest sensitivity to the assumed vaporization enthalpy for all aging schemes. This can be explained by the intricate interplay between the changes in partitioning of the semivolatile compounds and their gas-phase chemical aging reactions. The same set of different parameterizations of the organic aerosol (OA) formation and evolution in the two-dimensional Volatility Basis Set (2D-VBS) framework are evaluated using ground measurements collected in the 2013 PEGASOS field campaign in the boreal forest station of Hyytiälä in Southern Finland. The most successful is the simple functionalization scheme of Murphy et al. (2012) while all seven aging schemes have satisfactory results, consistent with the ground measurements. Despite their differences, these schemes predict similar contributions of the various OA sources and formation pathways. Anthropogenic SOA is predicted to contribute 11- 18% of the total OA, while SOA from intermediate volatility compounds oxidation another 18- 27%. The highest contribution comes from biogenic SOA, as expected contributing 40 to 63% depending on the modeling scheme. The primary OA contributes 4% while the SOA resulting from the oxidation of the evaporated POA varies between 4 to 6%. Finally, 5-6% is according to the model the results of long range transport from outside the modeling domain.</p

Simulating Atmospheric Organic Aerosol in the Boreal Forest Using Its Volatility-Oxygen Content Distribution

Various parameterizations of organic aerosol (OA) formation and its subsequent evolution in the two-dimensional Volatility Basis Set (2D-VBS) framework are evaluated using ground measurements collected in the 2013 PEGASOS field campaign in the boreal forest station of Hyytiälä in southern Finland. A number of chemical aging schemes that performed well in the polluted environment of the Po Valley in Italy during the PEGASOS 2012 campaign are examined, taking into account various functionalization and fragmentation pathways for biogenic and anthropogenic OA components. All seven aging schemes considered have satisfactory results, consistent with the ground measurements. Despite their differences, these schemes predict similar contributions of the various OA sources and formation pathways for the periods examined. The highest contribution comes from biogenic secondary OA (bSOA), as expected, contributing 40–63% depending on the modeling scheme. Anthropogenic secondary OA (aSOA) is predicted to contribute 11–18% of the total OA, while SOA from intermediate-volatility compounds (SOA-iv) oxidation contributes another 18–27%. The fresh primary OA (POA) contributes 4%, while the SOA resulting from the oxidation of the evaporated semivolatile POA (SOA-sv) varies between 4 and 6%. Finally, 5–6% is predicted to be due to long-range transport from outside the modeling domain

Mineral dust modeling for optimizing operation and maintenance procedures in concentrated solar power plants

Concentrated solar power (CSP) plants are being implemented in dusty environments such as the Middle East and North Africa where solar radiation is high. However, these areas are usually dry and typically have scarce water resources. The minimization of soiling-induced losses together with the reduction of cleaning costs is a challenge for operators and project planners. The H2020SOLWATT project targets to significantly reduce the water used by CSP plants. Within SOLWATT, our goal is to implement an operational soiling rate forecast product for the Middle East, North Africa and Europe. The product will be based on the combination of the MONARCH dust forecast System developed and operated by the Barcelona Supercomputing Center and an empirical soiling model developed by the DLR Institute of Solar Research. The resulting soiling forecast system is expected to help operators optimizing cleaning schedules and to serve as an input to a Dispatch and Operation & Maintenance optimizer. MONARCH is based on the online coupling of the meteorological Nonhydrostatic Multiscale Model with a full aerosol-chemistry module. The model provides operational regional mineral dust forecasts for the World Meteorological Organization (WMO; https://dust.aemet.es/), and participates to the WMO Sand and Dust Storm Warning Advisory and Assessment System for Northern Africa-Middle East-Europe (http://sds-was.aemet.es/). The DLR soiling model is a physical model that predicts the soiling rate for a CSP collector from weather parameters like wind speed, particle number concentration, relative humidity and temperature. The model has been optimized and validated using measurement data from two sites in Morocco and Spain. We evaluate forecasts from MONARCH against the AERONET SDA (Spectral De-Convolution Algorithm) AOD coarse product and deposition measurements in North Africa, Middle East and Spain. We also provide and evaluation of the coupled MONARCH-DLR soiling forecast system for various forecasting horizons with soiling rate data from two CSP operational sites

Physical and Chemical Properties of 3‑Methyl-1,2,3-butanetricarboxylic Acid (MBTCA) Aerosol

The properties and the chemical fate of later generation products of the oxidation of biogenic organic compounds are mostly unknown. The properties of fresh MBTCA aerosol, a later generation product of the oxidation of monoterpenes in the atmosphere, were determined combining an aerosol mass spectrometer (AMS), a thermodenuder, and a scanning mobility particle sizer. Based on its AMS spectrum <i>m</i>/<i>z</i> 141.055 (C₇H₉O₃⁺) could be used as an MBTCA signature. The MBTCA particle density was 1.43 ± 0.04 g cm^–3, its saturation concentration was (1.8 ± 1.3) × 10^–3 μg m^–3 at 298 K, and its vaporization enthalpy was 150 ± 15 kJ mol^–1. After OH radical exposure (∼1.2 days) and UV illumination the average aerosol O:C ratio decreased from 0.72 to 0.58–0.64 suggesting net fragmentation. Our findings suggest that the reactions of MBTCA with OH lead to CO₂ loss with or without an oxygen addition

Simulation of atmospheric organic aerosol using its volatility–oxygen-content distribution during the PEGASOS 2012 campaign

A lot of effort has been made to understand and constrain the atmospheric aging of the organic aerosol (OA). Different parameterizations of the organic aerosol formation and evolution in the two-dimensional volatility basis set (2D-VBS) framework are evaluated using ground and airborne measurements collected in the 2012 Pan-European Gas AeroSOls-climate interaction Study (PEGASOS) field campaign in the Po Valley (Italy). A number of chemical aging schemes are examined, taking into account various functionalization and fragmentation pathways for biogenic and anthropogenic OA components. Model predictions and measurements, both at the ground and aloft, indicate a relatively oxidized OA with little average diurnal variation. Total OA concentration and O : C ratios are reproduced within experimental error by a number of chemical aging schemes. Anthropogenic secondary OA (SOA) is predicted to contribute 15–25% of the total OA, while SOA from intermediate volatility compound oxidation contributes another 20–35%. Biogenic SOA (bSOA) contributions varied from 15 to 45% depending on the modeling scheme. Primary OA contributed around 5% for all schemes and was comparable to the hydrocarbon-like OA (HOA) concentrations derived from the positive matrix factorization of the aerosol mass spectrometer (PMF-AMS) ground measurements. The average OA and O : C diurnal variation and their vertical profiles showed a surprisingly modest sensitivity to the assumed vaporization enthalpy for all aging schemes. This can be explained by the interplay between the partitioning of the semi-volatile compounds and their gas-phase chemical aging reactions