Metrology of gaseous air pollutants

The need for mutual recognition of accurate measurement results made by competent laboratories has been very widely accepted at the international level e.g., at the World Trade Organization. A partial solution to the problem was made by the International Committee for Weights and Measures (CIPM) in setting up the Mutual Recognition Arrangement (CIPM MRA), which was signed by National Metrology Institutes (NMI) around the world. The core idea of the CIPM MRA is to have global arrangements for the mutual acceptance of the calibration certificates of National Metrology Institutes. The CIPM MRA covers all the fields of science and technology for which NMIs have their national standards. The infrastructure for the metrology of the gaseous compounds carbon monoxide (CO), nitrogen monoxide (NO), nitrogen dioxide (NO2), sulphur dioxide (SO2) and ozone (O3) has been constructed at the national level at the Finnish Meteorological Institute (FMI). The calibration laboratory at the FMI was constructed for providing calibration services for air quality measurements and to fulfil the requirements of a metrology laboratory. The laboratory successfully participated, with good results, in the first comparison project, which was aimed at defining the state of the art in the preparation and analysis of the gas standards used by European metrology institutes and calibration laboratories in the field of air quality. To confirm the competence of the laboratory, the international external surveillance study was conducted at the laboratory. Based on the evidence, the Centre for Metrology and Accreditation (MIKES) designated the calibration laboratory at the Finnish Meteorological Institute (FMI) as a National Standard Laboratory in the field of air quality. With this designation, the MIKES-FMI Standards Laboratory became a member of CIPM MRA, and Finland was brought into the internationally-accepted forum in the field of gas metrology. The concept of ‘once measured - everywhere accepted’ is the leading theme of the CIPM MRA. The calibration service of the MIKES-FMI Standards Laboratory realizes the SI traceability system for the gas components, and is constructed to enable it to meet the requirements of the European air quality directives. In addition, all the relevant uncertainty sources that influence the measurement results have been evaluated, and the uncertainty budgets for the measurement results have been created.Tunnustettujen asiantuntijalaboratorioiden tekemien luotettavien mittaustulosten vastavuoroinen tunnustaminen on ollut laajasti hyväksytty periaate kansainvälisellä tasolla. Käytännön ratkaisuna Kansainvälinen Painojen ja Mittojen Komitea (CIPM) laati sopimuksen kalibrointitodistusten vastavuoroisesta hyväksynnästä, ekvivalenssisopimus (Mutual Recognition Arrangement, CIPM MRA), jonka on hyväksynyt kansalliset metrologialaitokset maailmanlaajuisesti. CIPM MRA sopimuksen ydin on se, että sopimuksen piirissä olevat kansalliset mittanormaalilaboratoriot tunnustavat toistensa antamat mittaus- ja kalibrointitodistukset tasavertaisiksi. CIPM MRA sopimus kattaa kaikki tieteen ja teknologian osa-alueet, joilla kansallisilla metrologialaitoksilla on kansalliset mittanormaalit. Kaasumaisten yhdisteiden metrologinen järjestelmä hiilimonoksidin (CO), typpimonoksidin (NO), typpidioksidin (NO2), rikkidioksidin (SO2) ja otsonin (O3) osalta on rakennettu kansallisella tasolla Ilmatieteen Laitoksella (IL). Kalibrointilaboratorio rakennettiin Ilmatieteen Laitokselle täyttämään ilmanlaadun mittausten vaatimat kalibrointitarpeet sekä metrologiselle laboratoriolle asetetut vaatimukset. Laboratorio osallistui menestyksellisesti ensimmäiseen vertailuprojektiin, jonka tavoitteena oli selvittää ilmanlaatumittauksissa käytettävien kaasunormaalien valmistuksen ja analysoinnin senhetkinen tilanne. Kalibrointilaboratorion teknisen pätevyyden osoittamiseksi järjestettiin myös kansainvälinen arviointi. Arvioinnissa vahvistui laboratorion pätevyys suoriutua metrologialaboratoriolta vaadittavista tehtävistä. Niinpä Mittatekniikan keskus nimesi Ilmatieteen laitoksen kalibrointilaboratorion kansalliseksi mittanormaalilaboratorioksi pätevyysalueena ilmanlaatu. Tällä nimityksellä MIKES-IL mittanormaalilaboratorio tuli osalliseksi ekvivalenssisopimusta (CIPM MRA) ja Suomi kytkeytyi osaksi kansainvälisesti hyväksyttyä mittausjärjestelmää kaasujen metrologiassa. ’Kerran mitattu – kaikkialla hyväksytty’ on ekvivalenssisopimuksen johtava ajatus. Kalibrointien jäljitettävyys kaasujen osalta on MIKES-IL mittanormaalilaboratoriossa järjestetty SI-yksikköön. Samalla luotu jäljitettävyysketju täyttää Euroopan ilmanlaadun direktiiviin kirjatun vaatimuksen mittausten jäljitettävyydestä kansallisella tasolla. Laboratorio on laatinut kalibrointi- ja mittaustuloksille mittausepävarmuusbudjetin, mikä käsittää kaikki mittaustulokseen liittyvät epävarmuuskomponentit

Clean Shipping: Exploring the impact of emission regulation

The environmental impact of the maritime industry has been under much public discussion,culminating in 2015 when regulations limiting sulphur content from shipping vessels came intoeffect in the Baltic Sea. Since then, the maximum sulphur content of fuel used by all ships navigating the Sulphur Emission Control Area (SECA) must be no more than 0.1 per cent. Up-to-date information on thetechnical efficiency and socio-economic impacts of different clean shipping solutions and theircapacity to comply with the regulations, however, is currently very limited. In order to develop future environmental regulations, policy makers and authorities need more knowledge. The shipping industry also needs to make informed investment decisions. To allow for knowledge-based decision making, discussions are needed involving maritime authorities, policy makers, NGOs, and the private sector.We have answered questions on the shipping industry's compliance with environmentalregulations, examining the technical efficiencies of different techniques for removing pollutionfrom exhaust gases. We have also explored the cost-effectiveness of various compliancemeasures used across the industry.Modelling methods have enabled us to assess current and future compliance costs as well aslook at the effects on public health and the environment. We have taken a closer look at threecities in the region to spread best practice on air quality measurement and modelling at a localscale. We have provided analysis to make recommendations that will improve the welfare of thepeople of the Baltic Sea Region. For environmental regulation to be effective, compliance needs to be monitored and noncompliance needs to be sanctioned. We have also presented findings on compliance levels and reflect on the attitudes of ship-owners responsible for meeting the regulations.The project aims to support maritime businesses and economic growth. Clean shipping solutionsprovide the potential for businesses to innovate. The development of clean shipping technologiesleads to spin-off enterprises and allows European industry actors to lead the way in globalmarkets. The Baltic Sea Region is a forerunner in this respect, acting as a living laboratory forclean shipping. The effectiveness of SECA was analysed by comparing the costs and benefits of the regulation according to a framework presented in Lähteenmäki-Uutela et al. (2018). As part of this work, wehave developed a free web-based economic decision-making tool to help companies estimate investment costs and decide what investments to make to comply with SECA regulations.In addition to promoting technological development and improving future regulation, we havebeen active in sharing the results with the wider community. Finding ways to meet the increasingdemand for improved air quality will ultimately bring economic opportunities as well as wellbeingfor the people of the region.</p

Measurement report : Characterization of uncertainties in fluxes and fuel sulfur content from ship emissions in the Baltic Sea

Fluxes of gaseous compounds and nanoparticles were studied using micrometeorological methods at Harmaja in the Baltic Sea. The measurement site was situated beside the ship route to and from the city of Helsinki. The gradient (GR) method was used to measure fluxes of SO2, NO, NO2, O3, CO2, and Ntot (the number concentration of nanoparticles). In addition, the flux of CO2 was also measured using the eddy-covariance (EC) method. Distortion of the flow field caused by obstacles around the measurement mast was studied by applying a computation fluid dynamic (CFD) model. This was used to establish the corresponding heights in the undisturbed stream. The wind speed and the turbulent parameters at each of the established heights were then recalculated for the gradient model. The effect of waves on the boundary layer was taken into consideration, as the Monin-Obukhov theory used to calculate the fluxes is not valid in the presence of swell. Uncertainty budgets for the measurement systems were constructed to judge the reliability of the results. No clear fluxes across the air-sea nor the sea-air interface were observed for SO2, NO, NO2, NOx (= NO + NO2), O3, or CO2 using the GR method. A negative flux was observed for Ntot, with a median value of -0.23×109m-2s-1 and an uncertainty range of 31%-41%. For CO2, while both positive and negative fluxes were observed, the median value was -0.081μmolm-2s-1 with an uncertainty range of 30%-60% for the EC methods. Ship emissions were responsible for the deposition of Ntot, while they had a minor effect on CO2 deposition. The fuel sulfur content (FSC) of the marine fuel used in ships passing the site was determined from the observed ratio of the SO2 and CO2 concentrations. A typical value of 0.40±0.06% was obtained for the FSC, which is in compliance with the contemporary FSC limit value of 1% in the Baltic Sea area at the time of measurements. The method to estimate the uncertainty in the FSC was found to be accurate enough for use with the latest regulations, 0.1% (Baltic Sea area) and 0.5% (global oceans).publishedVersionPeer reviewe

Calibration gases for existing air quality directive pollutants at limit values (LV)

The European Directive (2008/50/EC) sets up, among other things, the limit values i.e. the maximum allowed concentrations at given time average in the air, for specified pollutants. Calibration of the measurement instruments needs to be performed at regular time intervals. In the framework of an European Joint Research Programme (JRP) named Metrology for Chemical Pollutants in Air (MACPoll) one task aims to provide harmonized dilution methods for air pollutant gases at low concentration for calibration and quality control purposes. The study focuses on the reactive gases nitrogen dioxide and sulphur dioxide at concentration levels corresponding to the limit values given in the European Directive (2008/50/EC). Nitrogen oxide (NO) is studied as well as NO2 because both of them are measured simultaneously for NOx. This work consists in improving the dilution methods for generating calibration standards for SO2, NO, NO2 at limit values and to validate them by an interlaboratory comparison

Winter storms accelerate the demise of sea ice in the Atlantic sector of the Arctic Ocean

Published version, licensed by the CC BY 4.0, available at http://dx.doi.org/10.1038/s41598-019-45574-5A large retreat of sea-ice in the ‘stormy’ Atlantic Sector of the Arctic Ocean has become evident through a series of record minima for the winter maximum sea-ice extent since 2015. Results from the Norwegian young sea ICE (N-ICE2015) expedition, a five-month-long (Jan-Jun) drifting ice station in first and second year pack-ice north of Svalbard, showcase how sea-ice in this region is frequently affected by passing winter storms. Here we synthesise the interdisciplinary N-ICE2015 dataset, including independent observations of the atmosphere, snow, sea-ice, ocean, and ecosystem. We build upon recent results and illustrate the different mechanisms through which winter storms impact the coupled Arctic sea-ice system. These short-lived and episodic synoptic-scale events transport pulses of heat and moisture into the Arctic, which temporarily reduce radiative cooling and henceforth ice growth. Cumulative snowfall from each sequential storm deepens the snow pack and insulates the sea-ice, further inhibiting ice growth throughout the remaining winter season. Strong winds fracture the ice cover, enhance ocean-ice-atmosphere heat fluxes, and make the ice more susceptible to lateral melt. In conclusion, the legacy of Arctic winter storms for sea-ice and the ice-associated ecosystem in the Atlantic Sector lasts far beyond their short lifespan

International Key Comparison CCQM-K226b and Pilot Study CCQM P50b (S02): Comparison of Primary Standards of Sulphur Dioxide (SO2) in Synthetic Air

Accurate measurements of sulphur dioxide at the concentrations found in ambient air have become essential to support monitoring and legislation concerned with air quality. In general, the primary element of quality assurance for field instruments is regular calibration using certified gas mixtures. The concentration range chosen for this Key Comparison (240 nmol/mol to 320 nmol/mol) is defined by appropriate European standards and is typical of similar levels used around the world. The travelling standards used for the comparison were prepared commercially by a supplier with a proven track record of preparing stable mixtures of the relevant gases. The coordinating laboratory (NPL) carried out stability checks on the mixtures and determined the amount fraction using a primary gravimetric permeation facility. These data were used to determine the drift rate (and uncertainty) of each standard. The results for the 11 participants in CCQM-K26.b and the one participant in CCQM-P50.b are presented in this report. Degrees of equivalence have been calculated based on a reference value (corresponding to the KCRV) derived from the primary gravimetric facility used by the coordinating laboratory.JRC.F.8-Sustainable Transpor

International Comparison CCQM-K51 - Carbon Monoxide (CO) in Nitrogen (5 µmol mol-1)

The first key comparison on carbon monoxide (CO) in nitrogen dates back to 1992 (CCQM-K1a). It was one of the first types of gas mixtures that were used in an international key comparison. Since then, numerous national metrology institutes (NMIs) have been setting up facilities for gas analysis, and have developed claims for their Calibration and Measurement Capabilities (CMCs) for these mixtures. Furthermore, in the April 2005 meeting of the CCQM (Consultative Committee for Amount of Substance) Gas Analysis Working Group, a policy was proposed to repeat key comparisons for stable mixtures every 10 years. This comparison was performed in line with the policy proposal and provided an opportunity for NMIs that could not participate in the previous comparison. NMISA from South Africa acted as the pilot laboratory. Of the 25 participating laboratories, 19 (76%) showed satisfactory degrees of equivalence to the gravimetric reference value. The results show that the CO concentration is not influenced by the measurement method used, and from this it may be concluded that the pure CO, used to prepare the gas mixtures, was not 13C-isotope depleted. This was confirmed by the isotope ratio analysis carried out by KRISS on a 1% mixture of CO in nitrogen, obtained from the NMISA. There is no indication of positive or negative bias in the gravimetric reference value, as the results from the different laboratories are evenly distributed on both sides of the key comparison reference value.JRC.H.2-Air and Climat

International Comparison CCQM-P28: Ozone at Ambient Level

We report a pilot study organized within the Consultative Committee for Amount of Substance (CCQM), in which the ozone reference standards of 23 institutes have been compared to one common reference, the BIPM ozone reference standard, in a series of bilateral comparisons carried out between July 2003 and February 2005. The BIPM, which maintains as its reference standard a standard reference photometer (SRP) developed by the National Institute of Standards and Technology (NIST, United States), served as pilot laboratory. A total of 25 instruments were compared to the common reference standard, either directly (16 comparisons) or via a transfer standard (9 comparisons). The comparisons were made over the ozone mole fraction range 0 nmol/mol to 500 nmol/mol. Two reference methods for measuring ozone mole fractions in synthetic air were compared, thanks to the participation of two institutes maintaining a gas-phase titration system with traceability of measurements to primary gas standards of NO and NO2, while the 23 other instruments were based on UV absorption. In the first instance, each comparison was characterized by the two parameters of a linear equation, as well as their related uncertainties, computed with generalized least-squares regression software. Analysis of these results using the Birge ratio indicated an underestimation of the uncertainties associated with the measurement results of some of the ozone standards, particularly the NIST SRPs. As a final result of the pilot study, the difference from the reference value (BIPM-SRP27 measurement result) and its related uncertainty were calculated for each ozone standard at the two nominal ozone mole fractions of 80 nmol/mol and 420 nmol/mol.JRC.H.4-Transport and air qualit