Occupational exposure to saw dust: a case study

ABSTRACT: Occupational exposure to saw dust is associated with the development of oncological diseases, namely nasopharyngeal cancers (about 44% are from nasal cavity and paranasal sinus cancers), in the wood and furniture industries, about 55.000, according to the (Associação das Indústrias de Madeira e Mobiliário de Portugal) AIMMP. It should be noted that since 1995 these dusts have been classified as carcinogenic, by The International Agency for Research on Cancer (IARC). The main objective of this study is to evaluate the exposure to saw dust, quantifying its concentration, comparing with values stipulated by existing legislation and standardization. In order to reach the objectives described above, total dust sampling was performed following the NIOSH0500 methodology, in several jobs, in three different carpentries. From the samplings performed, an average value of saw dust concentration was obtained in each workstation. After analyzing the values obtained in the measurements, performed in the real work context, it was verified there was legal non-compliance in the Garlopa workstation and values of the order of magnitude of the NP 1796 exposure limit values ELV, in the Manual Polishing workstation, in some of the Carpentry Workshops. However, if we consider the Scientific Committee on Occupational Exposure Limit (SCOEL) ELV we can state that only the Trimmer complies with the established ELV. Thus, corrective and/or preventive measures should be implemented by employers and preventive measures should be receptive by workers by implementing/complying to ensure the health and well-being of all, will be proposed.info:eu-repo/semantics/publishedVersio

Cold electrons at comet 67P/Churyumov-Gerasimenko

Context. The electron temperature of the plasma is one important aspect of the environment. Electrons created by photoionization or impact ionization of atmospheric gas have energies �10 eV. In an active comet coma, the gas density is high enough for rapid cooling of the electron gas to the neutral gas temperature (a few hundred kelvin). How cooling evolves in less active comets has not been studied before. Aims. We aim to investigate how electron cooling varied as comet 67P/Churyumov-Gerasimenko changed its activity by three orders of magnitude during the Rosetta mission. Methods. We used in situ data from the Rosetta plasma and neutral gas sensors. By combining Langmuir probe bias voltage sweeps and mutual impedance probe measurements, we determined at which time cold electrons formed at least 25% of the total electron density. We compared the results to what is expected from simple models of electron cooling, using the observed neutral gas density as input. Results. We demonstrate that the slope of the Langmuir probe sweep can be used as a proxy for the presence of cold electrons. We show statistics of cold electron observations over the two-year mission period. We find cold electrons at lower activity than expected by a simple model based on free radial expansion and continuous loss of electron energy. Cold electrons are seen mainly when the gas density indicates that an exobase may have formed. Conclusions. Collisional cooling of electrons following a radial outward path is not sufficient to explain the observations. We suggest that the ambipolar electric field keeps electrons in the inner coma for a much longer time, giving them time to dissipate energy by collisions with the neutrals. We conclude that better models are required to describe the plasma environment of comets. They need to include at least two populations of electrons and the ambipolar field

Model-Observation Comparisons of Electron Number Densities in the Coma of 67P/Churyumov–Gerasimenko During 2015 January

International audienceDuring 2015 January 9–11, at a heliocentric distance of ~2.58–2.57 au, the ESA Rosetta spacecraft resided at a cometocentric distance of ~28 km from the nucleus of comet 67P/Churyumov–Gerasimenko, sweeping the terminator at northern latitudes of 43°N–58°N. Measurements by the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis/Comet Pressure Sensor (ROSINA/COPS) provided neutral number densities. We have computed modeled electron number densities using the neutral number densities as input into a Field Free Chemistry Free model, assuming H2O dominance and ion-electron pair formation by photoionization only. A good agreement (typically within 25%) is found between the modeled electron number densities and those observed from measurements by the Mutual Impedance Probe (RPC/MIP) and the Langmuir Probe (RPC/LAP), both being subsystems of the Rosetta Plasma Consortium. This indicates that ions along the nucleus-spacecraft line were strongly coupled to the neutrals, moving radially outward with about the same speed. Such a statement, we propose, can be further tested by observations of H3O+/H2O+ number density ratios and associated comparisons with model results