Characterization of Equivalent Black Carbon at a regional background site in Central Europe: Variability and source apportionment☆.

Characterizing Black Carbon (BC) at regional background areas is important for better understanding its impact on climate forcing and health effects. The variability and sources of Equivalent Black Carbon (EBC) in PM10 (atmospheric particles with aerodynamic diameter smaller than 10 µm) have been investigated during a 5-year measurement period at the National Atmospheric Observatory Kosetice (NAOK), Czech Republic. Ground based measurements were performed from September 2012 to December 2017 with a 7-wavelength aethalometer (AE31, Magee Scientific). The contributions of fossil fuel (EBCff) and biomass burning (EBCbb) were estimated using the aethalometer model. Seasonal, diurnal and weekly variations of EBC were observed that can be related to the sources fluctuations and transport characteristic of pollutants predominantly associated with regional air masses recirculating over the Czech Republic and neighboring countries. The absorption Ångström exponent (α-value) estimated in summer (1.1 ± 0.2) was consistent with reported value for traffic, while the mean highest value (1.5 ± 0.2) was observed in winter due to increased EBCbb accounting for about 50% of the total EBC. This result is in agreement with the strong correlation between EBCbb and biomass burning tracers (levoglucosan and mannosan) in winter. During this season, the concentrations of EBCbb and Delta-C (proxy for biomass burning) reached a maximum in the evening when increasing emissions of wood burning in domestic heating devices (woodstoves/heating system) is expected, especially during the weekend. The diurnal profile of EBCff displays a typical morning peak during the morning traffic rush hour and shows a decreasing concentration during weekends due to lower the traffic emission.

Evaluation of nanoparticle emissions from a laser printer in an experimental chamber and estimation of the human particle dose.

The aim of this study was to evaluate the nanoparticle emissions from a laser printer in a chamber in conjunction with emissions from printers in a print room (PR) and to characterize the processes that lead to increased nanoparticle concentrations, as well as to estimate the human particle dose of the printers' users. Measurements were conducted in a small stainless steel environmental chamber under controlled conditions, where the evolution of particle size distributions (PSDs) with time and printed pages was studied in detail. Printer was generating nanoparticles (vast majority ˂ 50 nm with mode on ~ 15 nm) primarily during cold startup. Previously, 1-week sampling was also done in a PR at the Technical University of Crete, where the tested laser printer is installed along with three other printers. Similarly, as it was observed in the chamber study, printers' startup on any given day was characterized by a sharp increase in particle number (PN) concentrations. Average measured PN concentrations during printing hours in PR (5.4 × 103 #/cm3) is similar to the one observed in chamber measurements (6.7 × 103 #/cm3). The ExDoM2 dosimetry model was further applied to calculate the deposition of particles in the human respiratory tract. More precisely, the increase in particle dose for an adult Caucasian male was 14.6- and 24.1-fold at printers' startup, and 1.2- and 5.2-fold during printing in the PR and experimental chamber, respectively, compared to the exposure dose at background concentrations (BCs).

Manikin-based size-resolved penetrations of CE-marked filtering facepiece respirators.

The purpose of this manikin-based study was to determine the percentage penetrations of nine CE-marked filtering facepiece respirator models (two samples from each) from filtering classes FFP1, FFP2, and FFP3 and to demonstrate by an independent measurement method the disadvantages and shortcomings of the currently valid European Norm (EN 149:2001) for filtering facepieces. All of the filtering facepieces were evaluated size-selectively in an experimental chamber using charge-neutralized monodisperse ammonium sulfate in 9 sizes ranging from 20-400 nm of count median diameter (CMD) under flowrate of 95 L/min. The results were then compared to the previous study concerning penetrations of 47-mm diameter filters cut from the filtering material of identical filtering facepieces. Although these two experimental methods for measuring penetrations of filtering materials from filtering facepieces are in good agreement (R2 = 0.91), the results show within-respirator variations in all three filtering classes (5.5-19.3% for all FFRs in FFP1, 2.8-8.5% in FFP2, and 0.1-2.8% in FFP3). The most penetrating particle size (MPPS) in this study was found to be in the range of 25-65 nm (CMD), which is in agreement with the range of 30-60 nm found in the previous study. Moreover, 7 out of 9 FFR models reached higher penetrations from manikin-based respirator measurements than during measurements of filters from the respective respirators. Furthermore, penetration levels increased up to ∼50% when the respirator was not sealed around the face of the manikin, indicating that the real protection level provided by these filtering facepieces may be even lower if the respirator does not fit perfectly. Considering that poor filtration efficiency and poor fit may increase under real work conditions, the particle penetration is even higher than was found in this study. Therefore, the CE-marked respirators examined in this study may not be efficient in providing the expected level of protection for workers exposed to nanoparticles.