Search

POD diffusive samplers loaded with Carbopack X and Carbograph 5TD were exposed to certified calibration mixtures containing a total of 110 different ozone precursor and air toxic compounds. Constant sampling rates were identified for 39 ozone precursors and 33 air toxics. As 9 of these compounds were included in both mixtures, this meant a total of 63 different volatile and very volatile compounds were sampled using the POD with overall expanded uncertainties below 30 % for the sampling rate associated with the whole range of sampling times from 2 to 24 h.Carbograph 5TD exhibited superior performance for diffusive sampling of oxygenated and halogenated compounds in the air toxics mixture, while Carbopack X showed higher sampling efficiencies for aliphatic and aromatic hydrocarbons, as well as halogenated compounds derived from benzene and C2 carbon number hydrocarbons.A model has been developed and applied to estimate sampling rates, primarily for the more volatile and weakly adsorbed compounds, as a function of the collected amount of analyte and the exposure time. For an additional 9 ozone precursors on Carbopack X, and 11 air toxics on Carbograph 5TD, the expanded uncertainties of modelled sampling rates were reduced to below 30 % and have a significantly reduced uncertainty compared to those associated with an averaged sampling rate.The paper provides Freundlich’s isotherm parameters for the estimated (modelled) sampling rates and defines a pragmatic approach to their application. It does so by identifying the best sampling time to use for the expected exposure concentrations and associated analyte masses. This allows for expansion of the sampling concentration range from hundreds ng m−3 to mg m−3, while avoiding saturation of the adsorbent.Finally, field measurement comparisons of POD samplers, pumped tube samplers and online gas chromatography (GC), for sampling periods of 3 and 7 days in a semi-rural background area, showed no significant differences between reported concentrations.

The performance of 18 European institutions involved in long-term non-methane hydrocarbon (NMHC) measurements in ambient air within the framework of the Global Atmosphere Watch (GAW) and the European Monitoring and Evaluation Programme (EMEP) was assessed with respect to data quality objectives (DQOs) of ACTRIS (Aerosols, Clouds, and Trace gases Research InfraStructure Network) and GAW. Compared to previous intercomparison studies the DQOs define a novel approach to assess and ensure a high quality of the measurements. Having already been adopted by GAW, the ACTRIS DQOs are demanding with deviations to a reference value of less than 5 % and a repeatability of better than 2 % for NMHC mole fractions above 0.1 nmol mol−1. The participants of the intercomparison analysed two dry gas mixtures in pressurised cylinders, a 30-component NMHC mixture in nitrogen (NMHC_N2) at approximately 1 nmol mol−1 and a whole air sample (NMHC_air), following a standardised operation procedure including zero- and calibration gas measurements. Furthermore, participants had to report details on their instruments and assess their measurement uncertainties. The NMHCs were analysed either by gas chromatography–flame ionisation detection (GC-FID) or by gas chromatography–mass spectrometry (GC-MS). For the NMHC_N2 measurements, 62 % of the reported values were within the 5 % deviation class corresponding to the ACTRIS DQOs. For NMHC_air, generally more frequent and larger deviations to the assigned values were observed, with 50 % of the reported values within the 5 % deviation class. Important contributors to the poorer performance in NMHC_air compared to NMHC_N2 were a more complex matrix and a larger span of NMHC mole fractions (0.03–2.5 nmol mol−1). The performance of the participating laboratories were affected by the different measurement procedures such as the usage of a two-step vs. a one-step calibration, breakthroughs of C2–C3 hydrocarbons in the focussing trap, blank values in zero-gas measurements (especially for those systems using a Nafion® Dryer), adsorptive losses of aromatic compounds, and insufficient chromatographic separation.

Abstract Diffusive sampler monitoring techniques were employed during wintertime studies from 2009 to 2012 to assess the spatial distribution of air pollutants associated with the Pinedale Anticline and Jonah Field oil and natural gas (O&NG) developments in the Upper Green River Basin, Wyoming. Diffusive sampling identified both the extent of wintertime ozone (O3) episodes and the distributions of oxides of nitrogen (NOx), and a suite of 13 C5+ volatile organic compounds (VOC), including BTEX (benzene, toluene, ethylbenzene and xylene isomers), allowing the influence of different O&NG emission sources to be determined. Concentration isopleth mapping of both diffusive sampler and continuous O3 measurements show the importance of localized production and advective transport. As for O3, BTEX and NOx mixing ratios within O&NG development areas were elevated compared to background levels, with localized hotspots also evident. One BTEX hotspot was related to an area with intensive production activities, while a second was located in an area influenced by emissions from a water treatment and recycling facility. Contrastingly, NOx hotspots were at major road intersections with relatively high traffic flows, indicating influence from vehicular emissions. Comparisons of observed selected VOC species ratios at a roadside site in the town of Pinedale with those measured in O&NG development areas show that traffic emissions contribute minimally to VOCs in these latter areas. The spatial distributions of pollutant concentrations identified by diffusive sampling techniques have potential utility for validation of emission inventories that are combined with air quality modeling.

El concepto de exposición de la población como un indicador directo del impacto de la contaminación sobre la salud pública es una consecuencia lógica del hecho de definir como objetivo primordial de las medidas de calidad del aire la protección de la salud del individuo. En este artículo se presenta la exposición a contaminantes en aire en diversos ámbitos como: la higiene industrial, la contaminación de ambientes interiores y su repercusión sobre la legislación de calidad del aire. La disminución del riesgo de salud de la población a la exposición de contaminantes en aire abre numerosos retos a la hora de definir indicadores de exposición, estrategias de control y evaluaciones efectivas de la exposición de la población.The concept of population exposure as a direct indicator of the impact of pollution on public health is a consequence of the fact that the final aim of air quality measurements is the protection of the individuals' health. This article presents a picture of the exposure to air pollutants in different environments: industrial hygiene, indoor pollution and air quality legislation. The reduction of the health risk of the population to air pollution exposure opens new challenges when defining exposure indicators, control strategies and an effective assessment human exposure.

The ambient air in Northern Italy is characterised by relatively high PAH and PM10 concentrations in relation to calm wind and intensive temperature inversions, especially during cold periods. These stagnant conditions are occasionally interrupted by North-Föhn events, which cause a drop in relative humidity and an increase in O3 levels, indicating the mixing of local and free troposphere air flows. In this study the influence of the North-Föhn on concentrations of tracer organic compounds, including polycyclic aromatic hydrocarbons (PAHs), PM10, O3 and black carbon (BC) was studied during a North-Föhn event in November 2007. Large fluctuations in the concentration of these compounds, as well as changes in PM10 composition due to daytime and night-time variations of local source emissions were observed. Although these events occur at low frequencies (6–10%) they can for short periods, strongly affect the regional air quality by quickly decreasing the concentrations of these tracer organic compounds. [Copyright &y& Elsevier]

Reference materials for particulate matter (PM) on filter media are not available for the quantification of polycyclic aromatic hydrocarbons (PAHs) in ambient air. This is due to the difficulty of obtaining reference material that has a homogeneous distribution on a filter surface that is large enough for characterization and distribution. High volume sample filters from different locations and seasons were considered to validate the feasibility of the use of quartz filters as reference material for PAH concentrations. A rapid thermal desorption (TD) technique coupled with gas chromatography/mass spectroscopy was applied to characterise the material for the content of fifteen different PAHs. TD technique allowed for rapid and accurate analysis of small sections of filter (5mm diameter), leaving enough material for the production of twenty sub-filter cuts (42 mm diameter) that could be used for distribution and control. Stability and homogeneity tests required for material certification were performed as indicated by the ISO guide 34:2009 and ISO 35:2006. The contribution of the heterogeneous distribution of PAHs on the filter surface resulted generally lower than 10% and higher for more volatile PAHs. One year of storage at -18°C indicated no significant variation in PAH concentrations. Nevertheless, a methodology for shipping and storing of the filter material at ambient temperature in especially designed plastic envelopes, was also shown to allow for stabile concentrations within twenty days. The method accuracy was confirmed by the analysis of NIST SRM 1649a (urban dust) and PAH concentrations were validated against the reference values obtained from an inter-laboratory exercise. In the case of benzo[a]pyrene for masses quantified between 100 pg and 10 ng the TD method provided expanded uncertainties of circa 10%, while the inter-laboratory reference value uncertainties ranged between 15 and 20%. The evaluation of these results supports the use of the presented methodology as a valid approach for the certification of PAH concentrations in PM10 quartz filters. The methodology allows for the production of a certificate of analysis for a single high volume filter, the concentration of which can easily be adjusted by selecting an appropriate sampling location., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The ambient air in Northern Italy is characterised by relatively high PAH and PM10 concentrations in relation to calm wind and intensive temperature inversions, especially during cold periods. These stagnant conditions are occasionally interrupted by North-Föhn events, which cause a drop in relative humidity and an increase in O3 levels, indicating the mixing of local and free troposphere air flows. In this study the influence of the North-Föhn on concentrations of tracer organic compounds, including polycyclic aromatic hydrocarbons (PAHs), PM10, O3 and black carbon (BC) was studied during a North-Föhn event in November 2007. Large fluctuations in the concentration of these compounds, as well as changes in PM(10) composition due to daytime and night-time variations of local source emissions were observed. Although these events occur at low frequencies (6-10%) they can for short periods, strongly affect the regional air quality by quickly decreasing the concentrations of these tracer organic compounds., (Copyright (c) 2010 Elsevier Ltd. All rights reserved.)

Polycyclic aromatic hydrocarbons (PAH) were analyzed from ambient air particulate matter (PM10) that was collected near Lago Maggiore (Lombardy) in Northern Italy from August 2008 to January 2009. Highest individual PAH concentrations ranged from 0.05 ng/m3 during mid-days in summer to about 6 ng/m3 duringthe nights of the coldest period. A multivariate experimental regression model for the estimation of PAH concentrations was used to apportion the identified local sources of PAHs. This model included specific markers (i.e., levoglucosan for wood combustion and hopanes for traffic emission) and meteorological parameters (i.e., ambient air temperature and atmospheric mixing layer heights). In autumn and winter, wood combustion on a daily average contributed from 30 to 70% to the PAHs in ambient air PM10. In this period, the contribution of the wood combustion was less than 30% during mid-day, increasing sometimes to more than 80% during the night In the samples taken during the summer period, traffic contribution to PAH concentrations was about 30%, while wood combustion was insignificant.