Gas and aerosol metrology for air quality and climate

This session invites contributions to address the fundamental metrology needed to underpin long term ambient monitoring of trace gases and aerosols, ensuring coherent and comparable measurements. This includes but is not limited to novel measurement methods or instruments and their metrological validation, development of novel reference materials, the determination and evaluation of uncertainties from sampling, calibrating and modelling, quality control and assurance procedures and instrumental and data comparisons. Monitoring long term spatial and temporal changes in ambient measurements of gaseous compounds and aerosols are essential to establish the scientific links and feedbacks between atmospheric composition, air quality and climate and to ensure legislative compliance. Ambient amount fractions and stable isotope ratios of many trace gases, including the major greenhouse gases (CO2, CH4 and N2O), as well as particle number concentrations and size distributions are routinely observed within networks of monitoring sites and on mobile measurement platforms around the globe. Ensuring the quality and comparability of all these measurement datasets is critical to improve reliability and reduce uncertainty in our understanding of the Earths system.

Convener: Dave Worton | Co-conveners: Paul Brewer, Céline Pascale, Stefan Reimann, Joële Viallon
vPICO presentations
| Tue, 27 Apr, 15:30–17:00 (CEST)

vPICO presentations: Tue, 27 Apr

Chairperson: Dave Worton
Sergey Assonov

For stable isotope data sets to be compared or combined in biogeochemical studies, their compatibility must be well understood. For δ13C measurements in greenhouse gases, the WMO GAW program has set compatibility targets of 0.010 ‰ for atmospheric CO2 and 0.020 ‰ for atmospheric methane (in background air studies [1, 2]). The direct comparison of samples between laboratories can provide limited information, such as a snapshot for a specific time period, but combining data sets produced over decades requires more efforts. To produce high quality data, reliable calibrations must be made, mutually consistent values of reference materials (RMs) must be used, and a traceability scheme that ensures low uncertainty must be implemented.

The VPDB δ13C scale provides example of approaches developed recently. Several problems with the existing implementation of the VPDB scale have been identified between 2009-2016 [3]: the primary reference material (RM) NBS19 was exhausted and needed to be replaced; the δ13C of LSVEC (used to anchor the VPDB scale at negative δ13C) was found to be drifting and its use as a RM for δ13C was discontinued [4]; other RMs that were available in 2016 (e.g., NBS18) were not able to be used to develop new RMs as their uncertainties were too large. Given that the VPDB scale is artefact-based and not supported by absolute ratio measurements with uncertainty as low as required, the principles of value assignments on the VPDB scale were needed to be revised.

To ensure that a revised scheme did not encounter similar problems (with dependence on a single scale-anchor), several fundamental metrological principles were considered: (i) traceability of measurement results to the primary RM, (ii) a hierarchy of calibrators and (iii) comprehensive understanding of measurement method(s) [5]. The revised VPDB scheme [3] was applied to the new primary RM [6] and three RMs covering a large δ13C range (to negative values) [7]. Values were assigned in a mutually consistent way, with uncertainties ranging from 0.010 to 0.015 ‰, depending on the assigned δ13C. Each RM value has an uncertainty assigned that includes all known instrumental corrections, potential alterations due to storage, and inhomogeneity assessment [6,7]. The scheme allows for the δ13C range to be expanded by developing new carbonate RMs, and to be extended to matrix-based RMs.

The revised VPDB δ13C scale realization should lead to a robust basis for improving data compatibility. The developed framework can be applied to other measurements of biogeochemical interest, such as small 17O variations (in H2O, carbonates and other samples), clumped isotopes, and various paleoclimate reconstructions. Notably, the traceability principle is helpful in realistic uncertainty estimations which provide a tool to understand constrains and limiting steps in data comparisons.

REFERENCES:  [1]. WMO, GAW Report No.229. 2016. [2]. WMO, GAW Report No.242. 2018. [3]. Assonov, S. et al., RCM, 2021. [4]. IUPAC, Press release of the IUPAC meeting in 2017, [5]. De Bievre, P. et al., PURE APPL CHEM, 2011. 83(10): p. 1873-1935. [6]. Assonov, S., et al., RCM, 2020: p. [7]. Assonov, S. et al., RCM, 2021.

How to cite: Assonov, S.: Metrological traceability of measurement results and calibration hierarchy is a prerequisite for improved data compatibility: example of the VPDB scale. , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11037,, 2021.

Lukas Flierl, Jelka Braden-Behrens, Javis Nwaboh, Olaf Rienitz, Olav Werhahn, and Volker Ebert

The emission of greenhouse gases and the resulting global warming is one of the most important and challenging issues of the 21st century. Carbon dioxide is one of the major contributors to the greenhouse effect and its atmospheric abundance has growing constantly since the beginning of the industrialization. The isotope ratios n(13C)/n(12C) and n(18O)/n(16O) are important tools for studying the impact of anthropogenic CO2. Usually, isotopic compositions of CO2 are reported as δ-values, that express isotope ratios relative to an artifact based on a fossil calcite called VPDB. This relative VPDB scale was necessary, since absolute and SI-traceable isotope ratios of CO2 are currently not available, neither by isotope ratio mass spectrometry (IRMS) nor by optical isotope ratio spectroscopy (OIRS). In this study we present a potential way of deriving absolute carbon and oxygen isotope ratios of carbon dioxide via IRMS based on the gravimetric mixture approach. Besides practical improvements like an air buoyancy correction scheme for masses of gases, we show first results applying our method which demonstrate its feasibility, limitations, and achievable uncertainties. Also, we show the mathematics behind our approach and discuss further improvements and applications. Furthermore, we show how these absolute ratios can be used in field applications by OIRS methods including a new approach on OIRS uncertainty assessments according to the GUM. For this contribution we report on our recent results within in the European metrology research projects SIRS (16ENV06). and STELLAR (19ENV05).

How to cite: Flierl, L., Braden-Behrens, J., Nwaboh, J., Rienitz, O., Werhahn, O., and Ebert, V.: Towards SI-traceable Isotope Ratios of Greenhouse Gases, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16568,, 2021.

Rodrigo Rivera Martinez, Diego Santaren, Olivier Laurent, Ford Cropley, Cecile Mallet, Gregoire Broquet, Michel Ramonet, Christopher Caldow, Pramod Kumar, Bonaventure Fontanier, Adil Shah, Luc Lienhardt, Mathis Lozano, Thomas Lauvaux, Leonard Rivier, Caroline Bouchet, Catherine Juery, and Philippe Ciais

Deploying a dense network of sensors around emitting industrial facilities allows to detect and quantify possible CHleaks and monitor the emissions continuously. Designing such a monitoring network with highly precise instruments is limited by the elevated cost of instruments, requirements of power consumption and maintenance. Low cost and low power metal oxide sensor could come handy to be an alternative to deploy this kind of network at a fraction of the cost with satisfactory quality of measurements for such applications.

Recent studies have tested Metal Oxide Sensors (MOx) on natural and controlled conditions to measure atmospheric methane concentrations and showed a fair agreement with high precision instruments, such as those from Cavity Ring Down Spectrometers (CRDS). Such results open perspectives regarding the potential of MOx to be employed as an alternative to measure and quantify CH4 emissions on industrial facilities. However, such sensors are known to drift with time, to be highly sensitive to water vapor mole fraction, have a poor selectivity with several known cross-sensitivities to other species and present significant sensitivity environmental factors like temperature and pressure. Different approaches for the derivation of CH4 mole fractions from the MOx signal and ancillary parameter measurements have been employed to overcome these problems, from traditional approaches like linear or multilinear regressions to machine learning (ANN, SVM or Random Forest).

Most studies were focused on the derivation of ambient CH4 concentrations under different conditions, but few tests assessed the performance of these sensors to capture CH4 variations at high frequency, with peaks of elevated concentrations, which corresponds well with the signal observed from point sources in industrial sites presenting leakage and isolated methane emission. We conducted a continuous controlled experiment over four months (from November 2019 to February 2020) in which three types of MOx Sensors from Figaro® measured high frequency CH4 peaks with concentrations varying between atmospheric background levels up to 24 ppm at LSCE, Saclay, France. We develop a calibration strategy including a two-step baseline correction and compared different approaches to reconstruct CH4 spikes such as linear, multilinear and polynomial regression, and ANN and random forest algorithms. We found that baseline correction in the pre-processing stage improved the reconstruction of CH4 concentrations in the spikes. The random forest models performed better than other methods achieving a mean RMSE = 0.25 ppm when reconstructing peaks amplitude over windows of 4 days. In addition, we conducted tests to determine the minimum amount of data required to train successful models for predicting CH4 spikes, and the needed frequency of re-calibration / re-training under these controlled circumstances. We concluded that for a target RMSE <= 0.3 ppm at a measurement frequency of 5s, 4 days of training are required, and a recalibration / re-training is recommended every 30 days.

Our study presents a new approach to process and reconstruct observations from low cost CH4 sensors and highlights its potential to quantify high concentration releases in industrial facilities.

How to cite: Rivera Martinez, R., Santaren, D., Laurent, O., Cropley, F., Mallet, C., Broquet, G., Ramonet, M., Caldow, C., Kumar, P., Fontanier, B., Shah, A., Lienhardt, L., Lozano, M., Lauvaux, T., Rivier, L., Bouchet, C., Juery, C., and Ciais, P.: Reconstruction of high frequency methane peaks from measurements of metal oxide low-cost sensors using machine learning, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16027,, 2021.

Shujiro Komiya, Fumiyoshi Kondo, Heiko Moossen, Thomas Seifert, Uwe Schultz, Heike Geilmann, David Walter, and Jost Lavric

Commercially available laser-based spectrometers permit continuous field measurements of water vapour (H2O) stable isotope compositions, yet continuous observations in the Amazon, a region that significantly influences atmospheric hydrological cycles on regional to global scales, are largely missing. In order to achieve accurate on-site observations in such conditions, these instruments will require regular on-site calibration, including for H2O concentration dependence ([H2O]-dependence) of isotopic accuracy.

With the aim of conducting accurate continuous δ18O and δ2H on-site observation in the Amazon rainforest, we conducted a laboratory experiment to investigate the performance and determine the optimal [H2O]-dependence calibration strategy for two commercial cavity-ring down (CRDS) analysers (L1102i and L2130i models, Picarro, Inc., USA), coupled to our custom-built automated calibration unit. We particularly focused on the rarely investigated performance of the instruments at atmospheric H2O contents above 35,000 ppm, a value regularly reached at our site.

The later analyser model (L2130i) had better precision and accuracy of δ18O and δ2H measurements with a less pronounced [H2O]-dependence compared to the older L1102i. The [H2O]-dependence calibration uncertainties did not significantly change with calibration intervals from 28 h up to 196 h, suggesting that one [H2O]-dependence calibration per week for the L2130i and L1102i analysers is enough. This study shows that with both CRDS analysers, correctly calibrated, we should be able to discriminate natural diel, seasonal and interannual signals of stable water vapour isotopes in a tropical rainforest environment.


How to cite: Komiya, S., Kondo, F., Moossen, H., Seifert, T., Schultz, U., Geilmann, H., Walter, D., and Lavric, J.: Laboratory evaluation of water vapour concentration dependence of commercial water vapour isotope cavity ring-down spectrometers for continuous onsite atmospheric measurements in the Amazon rainforest, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15424,, 2021.

Edgar Flores, Faraz Idrees, Philippe Moussay, and Robert I. Wielgosz

The long-term monitoring of reactive gases, such as NO2, provides significant challenges for the development of gas standards that can demonstrate fit-for-purpose stability and accuracy.  Over the last fifteen years the BIPM’s primary gas facility for the dynamic production of mixtures of nitrogen dioxide in nitrogen, operating over the range (1 μmol/mol to 15 μmol/mol) has been shown to operate with a relative standards uncertainty of 0.4%. The system is based on continuous weighing of a permeation tube and on the accurate impurity quantification and correction of the gas mixtures using FT-IR.

The operation of the system has been demonstrated in two international comparisons organized by the CCQM Working Group on Gas Analysis (CCQM-GAWG), in 2009 and 2018, with the former demonstrating the requirement to correct for HNO3 impurities in gas standards produced in cylinders, and the more recent, the potential for non-linear decay in NO2 concentration in gas cylinder standards in the first 100 to 150 days following their production.

The CCQM-K74 (2009/2010) was organized, with all cylinders prepared by the one NMI (VSL) with the same surface treatment and characterized for stability and with reference values provided by the BIPM dynamic reference facility. The initial comparison identified small decay rates in the circulated standards, accounted for by the addition of an uncertainty to the reference value, and calculated to have been no more than 0.1 nmol/mol per day loss of NO2. However, the 2009 comparison did not examine standards maintained by individual participating institutes directly. The protocol of the CCQM-K74.2018 comparison, was modified so that the standards prepared by participating institutes (two per participant), were all directly measured at the BIPM against its dynamic reference facility. The modified protocol, although technically more challenging, has allowed the different decay rates in different cylinder preparations from different institutes to be identified, as well as the time dependence of these days rates.

The work has highlighted the challenges in NO2 standard development, and that fit-for-purpose standards can be obtained following appropriate protocols. Further development of these protocols is the focus of a number of research programmes, for example  METNO2 and MetroPEMS projects within the EMPIR programmes. Further activities at the BIPM facility are focused on validating the performance of NO2 dynamic reference systems below 1 μmol/mol and into the nmol/mol range, with the comparison of different dynamic reference systems, in support of future international comparisons and knowledge transfer activities.

How to cite: Flores, E., Idrees, F., Moussay, P., and Wielgosz, R. I.: Long term stability of dynamic reference systems for NO2 atmospheric monitoring, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7233,, 2021.

Simona Lukosiunaite, Steffen Dörner, Sebastian Donner, Bianca Lauster, Steffen Beirle, Julia Remmers, and Thomas Wagner

Inland waterway shipping is an important mode of freight transport in Europe with an extended network especially in Germany, e.g. the Rhine and Danube Rivers, and a variety of artificial channels. Nitrogen oxides (NOx = NO + NO2), which are also emitted by ships, play an important role in tropospheric chemistry. NOx contributes to the formation of tropospheric ozone and thus photochemical smog. Moreover, NOx affects human health and increases the acidification of ecosystems.  Monitoring of NOx emissions from inland waterway vessels could provide cities that are located along the rivers with valuable information about ship contribution to the pollution.

In this study, ground-based MAX-DOAS (Multi AXis-Differential Optical Absorption Spectroscopy) measurements were performed along the Rhine River. The aim is to derive NO2 emissions from individual ships. First sensitivity measurements showed that our Tube MAX-DOAS instrument is sensitive enough to detect a NO2 signal that can be attributed to passing ships. However, finding the optimal measurement mode to determine the emissions proves to be a challenging endeavour.

How to cite: Lukosiunaite, S., Dörner, S., Donner, S., Lauster, B., Beirle, S., Remmers, J., and Wagner, T.: Deriving Nitrogen Oxide emissions from inland waterway vessels using MAX-DOAS measurements, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2808,, 2021.

Daniel Westervelt, Celeste McFarlane, Faye McNeill, R (Subu) Subramanian, Mike Giordano, and Albert Presto

There is a severe lack of air pollution data around the world. This includes large portions of low- and middle-income countries (LMICs), as well as rural areas of wealthier nations as monitors tend to be located in large metropolises. Low cost sensors (LCS) for measuring air pollution and identifying sources offer a possible path forward to remedy the lack of data, though significant knowledge gaps and caveats remain regarding the accurate application and interpretation of such devices.

The Clean Air Monitoring and Solutions Network (CAMS-Net) establishes an international network of networks that unites scientists, decision-makers, city administrators, citizen groups, the private sector, and other local stakeholders in co-developing new methods and best practices for real-time air quality data collection, data sharing, and solutions for air quality improvements. CAMS-Net brings together at least 32 multidisciplinary member networks from North America, Europe, Africa, and India. The project establishes a mechanism for international collaboration, builds technical capacity, shares knowledge, and trains the next generation of air quality practitioners and advocates, including domestic and international graduate students and postdoctoral researchers. 

Here we present some preliminary research accelerated through the CAMS-Net project. Specifically, we present LCS calibration methodology for several co-locations in LMICs (Accra, Ghana; Kampala, Uganda; Nairobi, Kenya; Addis Ababa, Ethiopia; and Kolkata, India), in which reference BAM-1020 PM2.5 monitors were placed side-by-side with LCS. We demonstrate that both simple multiple linear regression calibration methods for bias-correcting LCS and more complex machine learning methods can reduce bias in LCS to close to zero, while increasing correlation. For example, in Kampala, Raw PurpleAir PM2.5 data are strongly correlated with the BAM-1020 PM2.5 (r2 = 0.88), but have a mean bias of approximately 12 μg m-3. Two calibration models, multiple linear regression and a random forest approach, decrease mean bias from 12 μg m-3 to -1.84 µg m-3 or less and improve the the r2 from 0.88 to 0.96. We find similar performance in several other regions of the world. Location-specific calibration of low-cost sensors is necessary in order to obtain useful data, since sensor performance is closely tied to environmental conditions such as relative humidity. This work is a first step towards developing a database of region-specific correction factors for low cost sensors, which are exploding in popularity globally and have the potential to close the air pollution data gap especially in resource-limited countries. 



How to cite: Westervelt, D., McFarlane, C., McNeill, F., Subramanian, R. (., Giordano, M., and Presto, A.: CAMS-Net: The Clean Air Monitoring and Solutions Network, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13912,, 2021.

Arindam Roy, Satoshi Takahama, Athanasios Nenes, Sumit Sharma, and Anju Goel

It is well established that the high level of particulate matter is a leading cause of premature mortality and disease worldwide and especially in South Asia (Global Burden of Disease Study, 2019). The ground-based air quality (AQ) monitoring stations are used to calculate economic loss, premature mortality and validate the conversed PM2.5 concentration from satellite-based Aerosol Optical Depth (AOD) data. Over India, 793 manual monitoring air quality (AQ) monitoring stations and 307 automated AQ monitoring station are presently operating under the aegis of National Air Quality Monitoring Programme and Central Pollution Control Board respectively. However, studies addressing the spatial representativeness of the data generated from the AQ monitoring stations over India are very limited and therefore, it is unclear that whether the existing stations are sufficient to reflect the average ambient AQ over different Indian cities. 

The present study intends to classify the existing AQ monitoring stations on the basis of spatial representativeness and derive a general conceptual framework for commissioning representative AQ monitoring sites for Indian cities. The methodology involves analysis of land use, populations and air quality data for the existing air quality stations in million plus Indian cities. A case study was conducted for Pune (18.5° N, 73.8° E), a western Indian metro city with 3.15 million population (Census, 2011). Using the night-time light data and high resolution PM2.5, population exposure hotspots over Pune city were identified. It was observed that not only at the midst of the municipal area, population exposure hotspots can be identified at the peripheral region of PMC/PNMC which certainly signify the role of rapid developmental activity and urban agglomeration over Pune city. The existing air quality monitoring sites are located majorly in the pollution hotspots in the city center region and therefore installing AQ monitoring stations (co-located  with weather station) at the rapidly developing parts of the city is highly recommended. The present land use pattern and the location of existing monitoring sites suggests lack of urban background monitoring stations which indicates the gap of knowledge in monitoring the average air quality responsible of long-term health effect over Pune. The prevalence of AQ monitoring stations in the road junction points and near to metro construction works might overestimate the exposure estimate of the general population in the city.   

How to cite: Roy, A., Takahama, S., Nenes, A., Sharma, S., and Goel, A.: The representativeness of ground-based air quality monitoring stations: observation and recommendation from Indian cities , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13197,, 2021.

Vijay K. Sagar, Lakshmi kanchana Asuri, Vijay P. Kanawade, and Rabindra K. Nayak

The high level of surface ozone (O3) concentration is produced from the various complex chemical reaction of oxides of nitrogen (NOx) and volatile organic compounds (VOCs) under varied meteorological conditions. It has severe effects on human health, vegetation, and as well on infrastructure. The guidelines value for surface ozone level was set 50 ppb for an 8-hours daily average by Indian National Ambient Air Quality Standard (INAAQS, 2009) and World Health Organization (WHO, 2005) for India and worldwide respectively. Identifying the primary source of high ozone events based on observation is challenging. The relationship of the surface measured O3 with carbon monoxide (CO) and water vapor content are useful to identify the possible source of origin for the increased O3 in the stratosphere, regional or local influence.

The continuous observation of O3, NOx, CO at 1 minute temporal resolution along with the meteorological parameter (1-hour temporal resolution) were taken during August 2014 to April 2017. All parameters were averaged to 8-hourly for further analysis. The high ozone events were identified based on exceeding the surface ozone concentration limit as discussed above (50 ppb). The relationship of the surface measured O3 and CO (∆O3/∆CO) and water vapor were used to explain the source of high ozone such as stratospheric origin and anthropogenic activity. The HYSPLIT’s backward air mass trajectories of the height of 1000 meters for 120 hours were calculated for the site to understand the dispersion of the pollutants. During the high ozone event, the average concentration of O3, NOx, and CO was found to be 55.46 ppb, 5.19 ppb, and 0.180 ppb respectively which were lower than the normal conditions. The positive correlation of O3 with CO (∆O3/∆CO) and low water vapor mixing ratio (10.0 g/kg) indicate regional or local influence on observed high ozone events.

The high ozone events were explained based on the distribution of the ozone precursors such as NOx, CO, and meteorological parameters such as relative humidity solar radiation, wind speed, and wind direction at local. The local high ozone concentration was supported by local chemistry such as the low concentration of CO and NOx. The relationship between O3 and CO was used to explain the source of high ozone events.

How to cite: K. Sagar, V., Asuri, L. K., P. Kanawade, V., and K. Nayak, R.: Ozone chemistry during high ozone event at semi-urban region, Shadnagar, in Southern India, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12787,, 2021.

Konradin Weber, Christian Fischer, Martin Lange, Tobias Pohl, Tim Kramer, Christoph Böhlke, and Detlef Amend

Instrumented UAS (unmanned aerial systems, drones) can substantially enhance the capabilities for the investigation of air pollutants, when equipped with the appropriate and customized air pollution measurement systems. Important advantages can be found in the exploration of vertical and horizontal pollutant profiles as well as in the determination of fugitive emissions. The HSD Laboratory for Environmental Measurement Techniques (UMT) has developed a series of different multicopter UAS for various measurement tasks and payloads. Additionally, different commercial UAS are used by UMT. The multicopter UAS are equipped, depending on the measurement task, with different specifically adopted lightweight measurement systems for aerosols (PM10, PM2.5, PM1, UFP, PNC, number size distributions) or gases like O3, SO2, NOX, CO2 and VOCs. All measurement systems were intercompared with certified standard measurement equipment before use to assure the quality of the measurement results. Moreover, physical samples of aerosols can be taken during the flight, which enables a chemical or REM analysis after the flight.

Additionally, UMT developed an on-line data transmission system, which allows the transmission of measurement data during the flights from the UAS to the ground for continuous monitoring. In this way concentration plumes can be tracked and hotspots can be pinpointed during the flight. This online data transmission system is independent of commercial platforms, can work on different radio frequencies in a push mode (presently on 2.4 GHz) and communicates with RS232 and I2C interfaces. Within several intercomparison studies this online data transmission proved a high reliability and correctness of transmitted data.

In addition to technical details of the UAS and instrumentation we present in this contribution the results of different measurement campaigns based on our UAS measurements:

  • Investigations of emissions from the Duesseldorf airport combining upwind and downwind UAS measurements. These investigations became of special interest, as due to the reduced air traffic caused by the Corona pandemia now single aircraft starts and landings could be monitored with their emissions at elevated altitudes.
  • Investigations of vertical concentration profiles above the city of Duesseldorf, which could be influenced by industrial sites in the north of Duesseldorf as well as by the Duesseldorf airport.
  • Investigations of vertical and horizontal pollution distributions near, at and around industrial sites in the Rhine Ruhr area, especially of metal industry plants and chemical plants.

These examples highlight the capabilities of UAS measurements, which will be further enhanced by planned simultaneous use of several UAS in parallel and joint tasks.

How to cite: Weber, K., Fischer, C., Lange, M., Pohl, T., Kramer, T., Böhlke, C., and Amend, D.: UAS measurements for the investigation of emissions of air pollutants at the Duesseldorf airport and industrial sites in the Rhine-Ruhr area, Germany, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16561,, 2021.

Marvin Dufresne, Thérèse Salameh, Thierry Léonardis, Grégory Gille, Ludovic Lanzi, Alexandre Armengaud, and Stéphane Sauvage

Volatile Organic Compounds (VOCs) play a key role in the atmospheric pollution, especially as they are precursors of secondary pollutants (ozone, secondary organic aerosols, etc.), and they are key tracers of many sources.. Previous studies in the Mediterranean region, which is a hotspot of air pollution and climate change, have shown a high organic pollution due to VOCs. Moreover, in the Western part of the Mediterranean, few studies have been conducted regarding VOCs despite frequent ozone pollution episodes still occurring especially in Marseille-France. Long-term high quality VOC datasets are therefore crucial for the evaluation of emission inventories used as inputs of the chemical-transport models. The objective of our work is to improve our knowledge regarding VOC source apportionment in Marseille with a focus on emissions related to shipping raising the need of high quality monitoring datasets. For the first time, a one year and half (March 2019 - August 2020) measurement campaign has been conducted in Marseille at an urban area representative site receiving air masses from the harbor. In addition to a large set of instruments, two on-line thermal-desorption gas chromatography flame ionization detector have been used for the continuous hourly measurement of 70 Non-Methane HydroCarbons (NMHCs) from 2 to 16 carbon atoms covering alkanes including IVOCs, alkenes, alkynes, aromatics. Here, we will focus on the metrological aspects of the analytical instruments (traceability, repeatability, etc.), intercomparison of common species measured with both instruments, as well as an intercomparison of several calibration methods developed for IVOC (C10 to C16) measurement. A special attention has been given to the uncertainty estimation following ACTRIS and WMO guidelines.  Finally, we will show an overview of the Positive Matrix Factorization (PMF) model results, applied to a necessarily large robust dataset of observations with the associated uncertainties.

How to cite: Dufresne, M., Salameh, T., Léonardis, T., Gille, G., Lanzi, L., Armengaud, A., and Sauvage, S.: High quality monitoring dataset needed for improving VOC emission knowledge in a Mediterranean port city , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15080,, 2021.

Bushra Atfeh, Erzsébet Kristóf, Róbert Mészáros, and Zoltán Barcza

This work focuses on indoor air quality measurements carried out in an apartment in the suburban region of Budapest. The measurements were made by an IQAir AirVisual node air quality monitor which is a so-called low-cost sensor capable to monitor PM2.5 and carbon dioxide concentration. In this study we analyze data measured during January 2017 that was characterized by an extreme air pollution episode in Budapest. The aim of the study was to calculate daily indoor PM2.5 concentrations that are comparable with the outdoor concentrations provided by the official Hungarian Air Quality Monitoring Network. Given the fact that AirVisual Pro provides data with irregular sampling frequency, data processing is expected to influence the calculated daily mean concentrations.  The results indicated that the uneven sampling frequency characteristic of AirVisual node indeed causes problems during data processing and has an effect on the calculated means. We propose a ‘best method’ for data processing for sensors with irregular sampling frequency.

How to cite: Atfeh, B., Kristóf, E., Mészáros, R., and Barcza, Z.: Indoor air quality assessment in a residential apartment in Budapest, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5583,, 2021.

Volker Ziegler, Markus Pesch, and Friedhelm Schneider

With the EDM264, GRIMM offers a [A1] solution for mobile short- and long-term measurements in outdoor areas and at production sites. For research as well as permanent areal observations on a near reference quality base.

The model EDM264 features a powerful and robust measuring cell based on optical particle counting (OPC) principle with all the advantages that users of GRIMM‘s portable aerosol spectrometers  are used to. The system is embedded in a compact weather-protection housing with all-weather sampling, heated inlet system, data logger and meteorological sensor.

With TSP, PM10, PM4, PM2.5, PM1 and PMcoarse, the EDM264  provides all fine dust fractions real-time, valid for outdoor applications and calculated with the proven GRIMM enviro-algorithm, as well as six additional dust mass fractions pm10, pm2.5, pm1, inhalable, thoracic and respirable for IAQ and workplace measurements.

This highly versatile instrument performs real-time monitoring of particle number, particle size and provides information on particle surface distribution as well as dust mass distribution. GRIMM‘s EDM264 has 31 equidistant size channels, which are PSL traceable.

A high-end data logger enables data acquisition and wireless communication via LTE, WLAN or wired via Ethernet. Backup copies of the measurement data are stored in the device directly.

The rinsing air function, which protects the laser and detector in the optical cell, further increases the reliability and long term stability of the EDM264 under different environmental and climatic conditions.

The entire sample volume flow of 1.2 L/min is analyzed by 100% in the optical cell, which assures excellent counting efficiency at low and high concentrations and complies to the ISO 21501-1standard for OPCs.

With  all  these  features,  the  EDM264 is a world-leading dust monitor for precise monitoring of particulate matter and particle number concentration. This highly reliable instrument is an indispensable tool for many users, who need to measure aerosol levels and air quality outdoors, on construction sites, or at production facilities.

Keywords — aerosol research, aerial observation, fence line monitoring, wild fire detection   

How to cite: Ziegler, V., Pesch, M., and Schneider, F.: Mobile- and Hot Spot Measurement with OPC based Dust Monitor EDM264, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9866,, 2021.

Gerhard Steiner, Harald Flentje, Minna Väkevä, Lothar Keck, and Joonas Vanhanen

Here, we present the final, commercially available, version of a mobility particle size spectrometer that is able to access the 1 nm particle size range for ambient atmospheric measurements.

The overall system performance was tested in a multitude of laboratory experiments, determining various size dependent parameters like DMA’s transfer function, DMA penetration efficiency, PSM and CPC counting efficiency. With the knowledge of these parameters, we are able to define a well-known overall system performance, a critical prerequisite for measurements that start at 1 nm sized particles.

The instrument originates from a collaboration of Grimm Aerosol Technik, Germany and Airmodus Ltd, Finland, combining a Grimm SMPS+C system with the Airmodus Particle Size Magnifier (PSM). Accordingly, it is named: PSMPS.

The main system components comprise a modified version of the short Grimm Differential Mobility Analyzer (Grimm S-DMA), the diethylene glycol-based PSM (Airmodus A10) and the new butanol-based CPC (Grimm 5417). The modified S-DMA is specially optimized for the transmission of small ions. Typically, it is operated with an aerosol sample flow rate of 2.5 L/min and a sheath flow rate of 10 L/min, allowing particle size distribution measurements from 1.1-55.7 nm. The PSM is used to lower the detection efficiency of the Grimm CPC below 2 nm in electrical mobility equivalent diameter. The new Grimm 5417 CPC is an upgraded version of the well-known 5416 CPC, that features two switchable aerosol sample flow rates of 0.3 and 0.6 L/min and also supplies the S-DMA with sheath airflow rates of either 3.0 or 10.0 L/min.

In this presentation, we will introduce the features and performance of the PSMPS system, will highlight some laboratory characterization tests and report the results from an ambient aerosol measurement campaign at the Hohenpeissenberg Observatory of the German meteorological service (DWD), monitoring new particle formation events starting at a particles size of 1nm.

How to cite: Steiner, G., Flentje, H., Väkevä, M., Keck, L., and Vanhanen, J.: Monitoring ambient aerosol size distributions from 1 – 55 nm with the GRIMM-AIRMODUS PSMPS , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12472,, 2021.

Claudio Crazzolara, Sabine Lüchtrath, Hagen Stosnach, and Andreas Held

In urban areas, a large number of people use public transport systems on a daily basis, and depending on the length of their commute, they spend a considerable amount of time in it. Part of the public transport system runs underground. Even though underground trains are powered by electric traction motors, the accumulation of airborne particles may be of concern due to limited air exchange in underground transport systems.

Initial measurements carried out in previous studies worldwide have shown that the air in a subway train station can be considerably more polluted with particulate matter than the air at a busy road junction. PM10 mass concentrations as high as 120 µg/m3 have been measured at a subway train station in Stuttgart. This is more than double the daily average PM10 limit value of 50 µg/m3 for outside air in Europe.

In order to study particulate matter concentrations in the underground transport system of Berlin (Germany) and potential particle sources, first semester students carried out preliminary measurements in a student project in January 2021. The students were equipped with handheld optical particle counters to study particulate matter levels at various locations of the underground transport system and at roadside station at street level for comparison. In additions, airborne particles were collected by using a single staged impactor, and subsequently analysed for their metal content using Total Reflection X-ray Fluorescence (TXRF) analysis.

The results indicate significantly elevated PM10 levels in underground train stations compared to street levels. Up to 35 times as much iron was found in the air of an underground train station compared to a busy street intersection at Potsdamer Platz. These high levels of iron suggest that a reason for the elevated concentrations of particulate matter in the underground system could be abrasion from wheels and rails.

This preliminary study sets the basis for a more comprehensive investigation of PM sources in public underground transport systems required to evaluate its effect on urban air quality.

How to cite: Crazzolara, C., Lüchtrath, S., Stosnach, H., and Held, A.: Measurements of airborne particles and chemical identification of metal content in a public underground transport system, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13599,, 2021.