This study presents the heavy metal results obtained during Finnish interlaboratory comparison (ILC) measurements made during 2019. The aim of this measurement campaign was to verify the skills of accredited emission measurement teams and also to evaluate the challenges that stack testing teams face in the future when emission levels decrease. ILCs have been organized in Finland since the 1970s. ILCs provide an important platform for stack testing teams so that they can verify their measurement skills and also for the dissemination of knowledge. The knowledge about the measurement standards and their requirements has improved among stack testing teams during past years in Finland. As emission levels get lower, they still need to pay more attention to some quality assurance procedures, e.g. to method and field blanks. Based on the observations of this ILC for heavy metals it can be noted that the challenges that stack testing teams face are related to the fact that no guidance is given in the standard reference methods EN 13211 and EN 14385 for example on the calculation of measurement uncertainties and how results below limit of quantification should be taken into account. These reference methods were suitable for their purpose at the time they were validated. However, emission levels are now more stringent and it is challenging to measure them with acceptable uncertainty criteria. As a consequence, there is a clear need for harmonized approaches in Europe for consistent implementation of standards and regulations. Key issues where guidance should be provided include realistic measurement uncertainties at low concentration levels, reporting low concentrations and guidance on how measurement uncertainties should be taken into account when the results are used for compliance assessment. The overall aim is to ensure that even with low emission levels, the emission measurement results would be transparent and robust throughout the EU. Implications: Interlaboratory comparison measurements between stack testing teams are the most important tool to verify the quality of the measurements. Participation in an appropriate ILC is often mandatory to successfully achieve accreditation under ISO/IEC 17025. Such campaigns also provide an efficient platform for dissemination of knowledge. In addition, ILCs can be used to clarify the challenges that teams nowadays face when measuring low emission levels, thus creating important information for the revision work of standards.
EN 14791 is a European Standard Reference method for the measurement of SO 2 in emissions. This standard is based on a wet-chemical method in which SO 2 present in flue gases is absorbed into an absorption solution containing hydrogen peroxide, and analyzed as sulfates after sampling. This study presents the results obtained when three portable automated measuring systems (P-AMS), based on Fourier-transform infrared (FTIR) spectroscopy, non-dispersive infrared (NDIR) and ultraviolet-fluorescence (UV) techniques, were compared to the Standard Reference Method for SO 2 (EN 14791) in order to verify whether they could be used as alternative methods (AM) to EN 14791. In the case of FTIR, the measurements were performed from hot and wet gas, without any conditioning. UV-fluorescence analyzers were equipped with dilution probes and one NDIR applied a permeation dryer, whereas the other had a chiller. Tests were carried out at concentration ranges from 0 to 200 mg/m 3 (n) and from 0 to 800 mg/m 3 (n) for testing of equivalency according to CEN/TS 14793 using a test bench. Equivalency test criteria were met for all tested P-AMS except for NDIR at the lower range. The SO 2 results measured with NDIR and the chiller were lower compared to the setup with NDIR and permeation. This was most probably due to the chiller causing absorption of SO 2 in the condensate. Tests were also carried out at field conditions, measuring the SO 2 emissions from a boiler combusting mainly bark. The same phenomena were observed in these tests as during the test bench study, i.e. the measurement setup with NDIR and the chiller gave the lowest results. These data demonstrated that the tested alternative methods (FTIR, UV-fluorescence, and NDIR) could be used instead of the standard reference method EN 14791, thus providing real-time calibration of automated measuring systems. It must however be emphasized that when measuring water-soluble gases, such as SO 2 , the choice of suitable conditioning technique is critical in order to minimize losses of the studied component in the condensate. Implications: Portable automated measuring systems (P-AMS) provide real-time information about emissions and their concentrations, thus offering significant advantages compared to wetchemical methods. This study presents results which can be used as a validation protocol to show that the tested P-AMS techniques (FTIR, NDIR, UV-fluorescence) could be used instead of EN 14791 (CEN 2017a) as alternative methods (AM), when paying attention to the selection of an appropriate conditioning technique.
BackgroundTransport container traffic carries millions of containers worldwide. To protect transported freight and inhibit the spread of foreign species, the containers are fumigated with chemicals, some of which having effect to central nervous system. Gas components and concentrations should be known to define safe handling procedures for each container. The Finnish Work Environment Fund and VTT funded and performed project to collect the needed information, including ventilation times, to support future work to prepare instructions.MethodsResearch contained literature studies and practical measurements for ventilation times.ResultsBased on the literature study, close 80 different volatile compounds were detected, including about 60 chemical substances classified due to their occupational health risk. About 15 of those were known fumigants, others were supposed to be evaporated from the freight. Methods typically used for the measurement of gas concentrations are indication tubes, small hand held detectors and gas analysers. Their reliability and investment cost varies a lot. Ventilation times of containers loaded using separate numbers of corrugated board boxes were tested in field conditions with different loading ratios, temperatures and with different external ventilation systems. Fully loaded containers had even 60 times longer ventilation time than containers loaded partially. Thus, the ventilation of containers can take even several days, depending on the temperature and ventilation procedures.ConclusionsTo prevent occupational risks during container handling, the concentrations of harmful substances in container must be known. Today, such measurements need several analysis methods. Safe handling procedures should be based on reliable data to conclude when the safe working environment with sufficient high security margin is achieved in the container.
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