The structure of a minimal nn-chart with two crossings II: Neighbourhoods of Γ1∪Γn−1\Gamma_1\cup\Gamma_{n-1}

Given a 2-crossing minimal chart $\Gamma$, a minimal chart with two crossings, set $\alpha=\min\{~i~|~$there exists an edge of label $i$ containing a white vertex$\}$, and $\beta=\max\{~i~|~$there exists an edge of label $i$ containing a white vertex$\}$. In this paper we study the structure of a neighbourhood of $\Gamma_\alpha\cup\Gamma_\beta$, and propose a normal form for 2-crossing minimal $n$-charts, here $\Gamma_\alpha$ and $\Gamma_\beta$ mean the union of all the edges of label $\alpha$ and $\beta$ respectively.Comment: 57 pages, 36 figure

Higher health effects of ambient particles during the warm season: Therole of infiltration factors

A large number of studies have shown much higher health effects of particulate matter (PM) during the warm compared to the cold season. In this paper we present the results of an experimental study carried out in an unoccupied test apartment with the aim of understanding the reasons behind the seasonal variations of the health effects due to ambient PM2.5 exposure. Measurements included indoor and outdoor PM2.5 mass and chemical composition as well as particle size distribution of ultrafine particles. Monitoring campaigns were carried out during summer and winter following a ventilation protocol developed to replicate typical occupant behaviour according to a questionnaire-based survey. Our findings showed that seasonal variation of the relationship between ambient and indoor mass concentrations cannot entirely explain the apparent difference in PM toxicity between seasons and size distribution and chemical composition of particles were identified as other possible causes of changes in the apparent PM toxicity. A marked decrease of ultrafine particles (<100\u202fnm) passing from outdoors to indoors was observed during winter; this resulted in higher indoor exposure to nanoparticles (<50\u202fnm) during summer. With regards to the chemical composition, a pooled analysis showed infiltration factors of chemical species similar to that obtained for PM2.5 mass with values increasing from 0.73 during winter to 0.90 during summer and few deviations from the pooled estimates. In particular, significantly lower infiltration factors and sink effect were found for nitrates and ammonium during winter. In addition, a marked increase in the contribution of indoor and outdoor sulfates to the total mass was observed during summer

Polar organic marker compounds in atmospheric aerosol in the PoValley during the Supersito campaigns. Part 1: Low molecular weight carboxylic acids in cold seasons

In the framework of the“Supersito”project, three intensive experimental campaigns were conducted in the Po Valley (Northern Italy) in cold seasons, such as late autumn, pre-winter and deep-winter, over three years from 2011 to 2013. As a part of a study on polar marker compounds, including carboxylic acids, sugar derivatives and lignin phenols, the present study reports a detailed discussion on the at-mospheric concentrations of 14 low molecular weight carboxylic acids, mainly dicarboxylic and oxo-hydroxy carboxylic acids, as relevant markers of primary and secondary organic aerosols. PM2.5samples were collected in two monitoring sites, representing urban and rural background sta-tions. The high acid concentrations can be explained by the large human emission sources in the urbanized region, combined with the stagnant atmospheric conditions during the cold seasons that accumulate the organic precursors and accelerate the secondary atmospheric reactions. The distribution profiles of the investigated markers suggest the dominant contributions of primary anthropogenic sources, such as traffic, domestic heating and biomass burning. These results are confirmed by comparison with additional emission tracers, such as anhydro-saccharides for biomass burning and fatty acids originated from different anthropogenic sources. In addition, some secondary constituents were detected in both sites, as produced by in situ photo-chemical reactions from both biogenic (e.g. pinonic acid) and anthropogenic precursors (e.g. phthalic and adipic acids). The impact of different sources from human activities was elucidated by investigating theweek pattern of carboxylic and fattyacid concentrations. Theweekly trends of analytes during the warmer campaign may be related to emissions from motor vehicle traffic and industrial activities. Otherwise, the random pattern of the markers suggests the prevalent contribution of primary emissions from residential heating in the colder deep-winter

PROGETTO SUPERSITO

The project is focused on a detailed study of some chemical, physical and toxicological parameters and on health, epidemiological and environmental assessment by interpretative models, in the atmosphere of Emilia-Romagna (Italy). The project rises from the necessity to improve  knowledge about environmental and health aspects of fine and ultrafine particles, in primary and secondary components, in the atmosphere. The project, structured in 7 workpackages, is organized in two measurement programmes: the routine one that has a mainly daily time resolution, and the intensive one with high time resolution and a higher chemical speciation than the routine one. The sampling sites are five: three in urban areas (Bologna, Parma and Rimini), one in a rural area (San Pietro Capofiume) and one in a remote area (Monte Cimone). Parallel to outdoor studies, a workpackage  is planned for indoor studies and chemical composition analysis with the  outdoor/indoor ratio for characterizing indoor human exposure to outdoor pollution.Le projet consiste en une étude détaillée des paramètres chimiques, physiques et météorologiques et une évaluation sanitaire, épidémiologique et l’environnementale (grâce à des modèles), dans l’atmosphère de la région Emilie-Romagne. L’objectif du projet est le progrès des connaissances sur les aspects environnementaux et sanitaires des particules fines et ultra-fines en composants primaires et/ou secondaires dans l’ atmosphère. Le projet, articulé en 7 lignes directrices,  est organisé en deux programmes de mesures: un programme de routine avec une fréquence temporelle surtout quotidienne et un programme intensif avec une fréquence temporelle èlevée et un éventail plus large de l'analyse.  Les sites de mesure sont au nombre de cinq:  trois dans la zone urbaine (Bologne, Parme et Rimini), un dans la zone rurale (San Pietro Capofiume) et un dans une région reculée (Monte Cimone). Parallèlement, une ligne directrice se concentre sur l’étude du rapport intérieur/extérieur des composants  de la qualité de l’air dans les bâtiments, pour caractériser l'exposition humaine à la pollution extérieure lorsque les sujets son à l’intérieur.Lo scopo del progetto è la realizzazione di uno studio integrato dell’inquinamento dell’atmosfera in Emilia-Romagna attraverso misure di parametri chimici, fisici, tossicologici e valutazioni sanitarie, epidemiologiche ed ambientali mediante modelli interpretativi. Il progetto nasce dalla necessità di migliorare le conoscenze relativamente agli aspetti ambientali e sanitari del particolato fine ed ultrafine, nelle componenti e/o secondarie, presente in atmosfera. Il progetto, strutturato in 7 linee progettuali, è organizzato in due programmi di misure: uno routinario in cui sono previsti campionamenti giornalieri ed uno intensivo in cui è prevista una speciazione più dettagliata con maggiore risoluzione temporale. I siti di campionamento sono 5: 3 in area urbana (Bologna, Parma e Rimini), 1 in  area rurale (San Pietro Capofiume) e 1 in area remota (Monte Cimone). Contestualmente agli studi outdoor è prevista una linea progettuale che si occupa dello studio del particolato, della sua composizione chimica nel rapporto qualità dell’aria outdoor/indoor e della caratterizzazione dell’esposizione della popolazione in ambienti indoor agli inquinanti tipici dell’ambiente outdoor

Field study of a soft X-ray aerosol neutralizer combined with electrostatic classifiers for nanoparticle size distribution measurements

Most conventional aerosol neutralizers are based on radioactive sources, which are controlled by strict regulations restricting their handling, transport, and storage. The TSI 3087 soft X-ray (SXR) neutralizer circumvents these legal restrictions. The aim of the present work is to compare the performance of a standalone SXR aerosol neutralizer with that of conventional radioactive aerosol neutralizers based on85Kr (TSI 3077) and241Am (Grimm 5522) by performing field tests in a real environmental scenario. The results obtained when the SXR neutralizer was connected to a mobility particle sizer spectrometer (MPS), different from the device suggested by the manufacturer, were comparable with those obtained with the use of radioactive aerosol neutralizers. In changing the neutralizer, the particle number concentrations, measured with the MPS connected to the SXR neutralizer, almost remained within the 10% uncertainty bounds for the particle size interval 10–300 nm, when diffusion losses inside the SXR tube were considered. Based on our comparisons, the SXR neutralizer can be regarded as a standalone instrument that could solve the problems associated with legal restrictions on radioactive neutralizers and fulfil the need for a portable instrument for different field test purposes

Reconstructing Elemental Carbon Long-Term Trend in the Po Valley (Italy) from Fog Water Samples

Elemental carbon (EC), a ubiquitous component of fine atmospheric aerosol derived from incomplete combustion, is an important player for both climate change and air quality deterioration. Several policy measures have been implemented over the last decades to reduce EC emissions from anthropogenic sources, but still, long-term EC measurements to verify the efficacy of such measurements are limited. In this study, we analyze the concentration of EC suspended in fog water samples, collected over the period 1997–2016 in a rural background site of the southern Po Valley. The comparison between EC in fog water and EC atmospheric aerosol concentration measured since 2012 allowed us to reconstruct EC atmospheric concentration from fog water chemical composition dating back to 1997. The results agree with the EC atmospheric observations performed at the European Monitoring and Evaluation Program (EMEP) station of Ispra in the northern part of the Po Valley since 2002, and confirm that the Po Valley is a pollution hotspot, not only in urban areas, but also in rural locations. The reconstructed trend over the period 1997–2016 indicates that EC concentration during the winter season has decreased on average by 4% per year, in agreement with the emission reduction rate, confirming the effectiveness of air quality measures implemented during the past 20 years

Influence of semi- and intermediate-volatile organic compounds (S/IVOC) parameterizations, volatility distributions and aging schemes on organic aerosol modelling in winter conditions

This study presents a high–resolution (5 km) set of new simulations performed with CAMx v6.40 over the Po Valley area (Northern Italy), aimed to enhance organic aerosol (OA) levels prediction and to gain insight into the sensitivity of CAMx to different uncertain features of the input setup. In particular, we mainly investigated the role of (i) volatility distributions of organic emissions, (ii) parametrizations of semi– and intermediate–volatile organic compounds (S/IVOC) emissions and (iii) different aging schemes, by exploiting the latest experimental information available in the recent scientific literature. Model results were validated against two OA–specific datasets, available for both an urban site (Bologna, February 2013) and a rural one (Ispra, March 2013). We found out a remarkable performance enhancement of modelled OA levels when applying revisions in S/IVOC emission parametrizations together with the new volatility distributions, at both the validation sites. This performance enhancement is associated with a very significant improvement in secondary organic aerosol (SOA) prediction, mainly due to revised IVOC emissions. At Bologna urban site, mean fractional bias (MFB) of OA ranged from −80.1% in the worst run to −10.1% in the best one and index of agreement (IOA) from 0.52 to 0.75. Notable improvements but overall poorer metrics were found for Ispra site, where MFB ranges from −84.2% to −35% and IOA from 0.45 to 0.50. These findings indicate that organic matter in the semi– and intermediate–volatile range are most likely underestimated in official emission inventories for each main source category (i.e. biomass burning, diesel and gasoline vehicles exhaust). Finally, model results did not show a very pronounced sensitivity to aging processes, due to the low photochemical activity typically observed during winter–time. However, we give evidence that enabling aging processes for biomass burning related SOA, which is by default disabled in CAMx v6.40, can help in closing the gap between modelled and observed SOA concentrations.JRC.C.5-Air and Climat