VERT NPTI Workshop - March 21st, 2024 - EMPA, Dübendorf

VERT would like to thank again All participants, presenters and sponsors that made such event an international great success with representation from all over Europe (DE, NL, BE, UK, NO, FI, CH,DK, FR, etc) as well as Chile, Colombia and North America. The movie of the NPTI Workshop technical conference and PN instrument exhibition (AVL, BARTEC, CAPELLEC, DEKATI, ENVIROCLEAN, HELLA-GUTMANN, KNESTEL, MAHLE, OPUS-INSPECTON, SAXON-JUNCALOR, SCALE, SENSORS, SNAP-on, TEN, TEXA, TSI) will be shortly available on the website. Below a summary of the VERT NPTI event.


NPTI - PN measurement during the periodic technical inspection of motor vehicles

VERT workshop on the "Review of the implementation experience" 21/03/2024 


From the very beginning (1995), VERT and the Swiss authorities introduced the number concentration of nanoparticles in exhaust gas as a criterion for the health risk and thus as a quality criterion for filters and developed corresponding measuring devices to replace the unsuitable smoke measurement and the misleading measurement of the particle mass. Twenty years ago, thanks to NanoMet 3, it was already possible to initiate PMP in order to enforce the number measurement for the approval of new vehicles in the EU and 15 years ago, handy devices such as the DiSCmini were already available for field monitoring.

In 2012, however, the EU decided to "delegate" the periodic emissions test to the electronic onboard control OBD, an unforgivable mistake with a complete loss of control, which ultimately led to the "VW emissions scandal" in 2015 and serious manipulations.

In a hearing of the German Bundestag in 2016, VERT advised the reintroduction of emissions controls, but with modern measuring devices that correspond to modern emissions technology. The Federal Republic of Germany adopted the proposal into law in January 2017, but new devices were not yet available. VERT then founded the informal NPTI working group with TNO and numerous experts, which, thanks to the support of the Dutch authorities and numerous measuring device manufacturers, succeeded in developing a completely new test procedure and a measurement procedure suitable for workshops and finalising the normative specifications in record time by 2019.

Following this, the political process to introduce number measurement for the PTI was started in 4 countries, the Netherlands, Belgium, Germany and Switzerland. Belgium was the quickest and officially started the measurements in mid-2022, the 3 others followed in 2023 and the EU included the proposals in a new roadworthiness directive in March 2023. Today, in March 2024, we already have more than 60,000 of these new measuring devices in use in vehicle workshops and test centres, more than 3 million vehicles have been measured using this method and have uncovered numerous failures (2-21% depending on the manufacturer, a shocking 6-10% on average), over 15 measuring device manufacturers offer their systems at unit prices < 8000 euros - a revolution in emissions measurement technology that will lead to a significant improvement in air quality worldwide.

VERT chose this time to invite the NPTI community to an implementation review, which met with great interest and was realised with an exhibition of almost all devices and the participation of over 100 experts and all interested authorities. New measuring instruments from AVL, BARTEC, CAPELLEC, DEKATI, ENVIROCLEAN, HELLA-GUTMANN, KNESTEL, MAHLE, OPUS-INSPECTON, SAXON-JUNCALOR, SCALE, SENSORS, SNAP-on, TEN, TEXA, TSI were exhibited, most of them are already certified by the national metrology authorities NMI, METAS and PTB.

The exhibition of the measuring devices was part of a technical conference at which the political decision-makers of the key countries NL, B, FRG and CH as well as the aforementioned central metrology authorities presented their experiences with the introduction. The major testing institutions such as TÜV, DEKRA, GOCA and MFK-Schweiz were able to present test results from several million vehicles and report on their experiences, according to which the introduction of the new test methods has generally gone quite smoothly. Particularly important was the exchange with participants from more than 20 nations, 10 of which will adopt the new PN-PTI method in the short term, including Chile and Colombia.

Although VERT has thus come much closer to the goal of eliminating the health risks and climate damage caused by combustion engines, as we expect NPTI to spread across the globe in a very short time after this rapid start, we are still far from reaching the end: this test method must be extended to all engines, including petrol engines, in order to quickly rid the large fleets of megacities of high-emission vehicles.

watch the video (german)

watch the video (english)


VERT NPTI Focus Event, July 7 th 2021


Alarming global mortality from fine particle pollution generated by fossil fuel  combustion 


Abstract:  Particulate air pollution from combustion has been associated with increases in deaths, heart attacks, strokes, and respiratory illness. Recent human studies and abundant toxicology indicate these associations are causal. Traffic particles, including ultrafine particles, have also been associated with many adverse outcomes and biological mechanisms. They also are more likely to get into people’s lungs because of where they are emitted. Recent studies demonstrate the magnitude of the effect, with many millions of deaths per year from particles due to fossil fuel combustion. While traffic particles are only part of those particles, they are critical to control.

Prof. J. Schwarz; Harvard University; US

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NPTI started in 2016, now completed with the VERT-Standard TA-024, the availability of new instruments and the implementation in three countries


Abstract: VERT introduced the PN criterion in 1996 to define filtration effectiveness of DPF in the solid particle size range of 10-500 nm. NanoMet, the first in-use PN-instrument was ready 1997 when VERT started to certify DPF and published the filter list. The EU adopted the PN criterion and the VERT PN metrology with PMP in 2007 as basis for the introduction of DPF and GPF, thereby reducing the PN-emission by 2-3 orders of magnitude in one step of the legislation. In 2012 however the EU abandoned the requirement of emission testing during the regular PTI believing that OBD would be sufficient for onboard emission control. As a consequence many DPF were de-installed and manipulated. TNO teamed up with VERT, JRC, the emission control of the NL and others to start the NPTI task force in Nov. 2016 to solve this problem by a simple PN test at low idle with. Now new low cost instruments are on the market; the Netherlands, Belgium and Germany have implemented the new low idle test and VERT offers support for the implementation of this new method to catch the high polluters and clean the air from ultrafine particles highly polluted cities.
A. Mayer; VERT, Switzerland

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In Belgium Emissions due to DPF failure rates are far too, which required implementation of  PTI with number count at low idle


Abstract: The first test campaign on PN-counters to introduce Particle Counting measurements in PTI was conducted in Belgium in 2018. The evaluated PN-counters were at that time not homologated against any specification. This is why we see differences between these PN counters used in the study. Nevertheless, the campaign highlighted a significant number of high polluting vehicles. The exhaust of the ultrafine particles of the Belgium fleet of all diesel vehicles will be reduced by 17% by eliminating these high polluting vehicles. Looking only to the euro 5 & 6 vehicles, and thus to the vehicles in the scope of PN-testing during PTI the reducing could be 98%. Hereafter Belgium started to prepare the implementation of the particle counter during PTI by 1/07/2022. The specifications of the equipment is, as in The Netherlands, based on the work of the NPTI workgroup. The Dutch NMi has this year homologated the first counters.  So a second test campaign with homologated equipment is right now running in Belgium. The presentation will highlight the evolution of the exhaust of the ultrafine particles on diesel vehicles based on these 2 campaigns.

 P. Beukenhoudt; GOCA, Belgium 



High emitters dominate PN emissions of petrol Light Duty Vehicles in Mexico City – and probably also in most other large cities


Abstract: Mexico City Metropolitan Area is one of the biggest cities of the world, there are around 5.3 million vehicles. In this study more than 400,000 light gasoline vehicle datasets of PN measurements were analyzed taken from the results of Mexico City´s Vehicle Inspection Program from 2018 to 2019. Measurements were made according to national and international standards. The results showed that 8% of the fleet contributes to the 58% of the total PN contamination of Mexico City. In conclusion, PN-measurement is a very sensitive parameter to detect high polluters and gasoline vehicles can emit equal or more PN emissions than diesel vehicles.

C. Dominguez; GESSPA, Mexico 

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PTI for the DPF-retrofitted public transport bus fleet in Chile


 Abstract: Santiago/Chile has 1500 Euro VI buses and will continue to increase the number as part of their new “Red Movilidad” fleet, along with electric buses. To ensure a high quality of maintenance and prepare for a new inspection process, Purexhaust was requested to survey particle numbers of various fleets, including Euro III + DPF and Euro V (without DPF). This presentation summarizes the results and analysis.

 N. Fraser; PUREXHAUST, Chile

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 PTI by PN at high idle for the Swiss DPF-since 2012 regulated


 Abstract: Together with the regulation to equip construction machines with DPF in 2002 the Swiss FOEN introduced a PTI regulation which required emission control every 24 month by free acceleration opacity (BauRLL 2002). 2012 replaced Swiss METAS the opacity measurement by number count at high idle and TSI NPET was the first instrument available for this measurement. Although not yet mandatory a large fleet of construction machines with DPF has been investigated and approximately 20% of DPF failed to fulfill  the emission limit of 250’000 P/cc. No correlation with age or brand was confirmed. This observation clearly demonstrated that this regular emission control is required, maybe more frequently and a second instrument (DC by FHNW) became available. Today PTI is required for construction and as well for commercial lake ships and lokomotives.

 J.Czerwinski / VERT, Switzerland

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Why is PTI for modern vehicles needed in addition to OBD, market surveillance and remote control


Abstract: The presentation will give an overview over certification and tests performed for emission control of vehicles at TÜV during the complete lifetime of a vehicle. In the phase of consumer operation of a vehicle proper maintenance and service as well as a periodic technical inspection (PTI) is of importance to control harmful vehicle tailpipe emissions.  With the introducion of electronic engine control, the vehicle can perform its own diagnostics (OBD), to help maintenance with helping identifying defective items, that cause high emissions. In the presentation it will be shown, that  the OBD system is not sensitive enough to detect for example cracked diesel particulate filters, that cause high emissions of ultra-fine particles, and therefore a new PTI tailpipe PN measurement is necessary. 
K. Matthies / TÜV, Germany

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From development to effective implementation of a particulate filter check


 Abstract: Several Dutch organisations have, since 2012, worked on the development of a new particle test to verify the correct functioning of diesel particulate filters. The test is conducted using an affordable, uncomplicated particle counter, capable of measuring high particle concentrations. It takes a mere 90 second, and is carried out with the engine idling. As a result of this development in 2022, the Dutch and Belgian authorities will introduce a compulsory particulate filter check in the periodic technical inspection based on the particle test. Germany will introduce a similar check in 2023. For a successful implementation of the particulate filter check in PTI workshops, a new nomenclature and additional communication are needed to inform policy makers and PTI inspectors.
G. Kadijk , ETS, Netherlands

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From the development of an instrument standard for VERT-NPTI to an internationalnew PTI  standard with PN counting at low idle


Abstract: Particulate emissions from combustion engines are a great problem in ambient air pollution. The introduction of very efficient (>99%) diesel particle filters (DPF) reduced the particle emissions from diesel engines substantially. However, already small defects in the filter can increase the emissions by orders of magnitude. These defects (or manipulations) cannot be detected by the on-board diagnostic system. Therefore, a number of countries decided to reintroduce a periodic technical inspection (PTI). PTI is needed to identify such high polluters, which are responsible for a very significant fraction of the fleet emissions, 10% of the cars are responsible for more than 80% of all emissions. In the framework of the NPTI working group a concept for PTI, including requirements for the instruments, measurement cycle and limit value has been elaborated. Kadijk et al [1] showed that the emissions in the test cycle correlate quite well with particle concentration measured in low idle. This allows to compare the limit in type approval testing with a limit, set for a test at low idle. A low idle measurement can be performed in less than a minute. Particle measurement by number concentration can be done by condensation particle counters (CPC), or diffusion charging (DC) based devices. Whereas number concentration is the established metric, used in type approval testing, other metrics as surface concentration of black carbon concentration could be used as well for PTI. Based on this, a VERT standard has now been suggested.
H.Burtscher / FHNW, Switzerland

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Legislation breakthrough in the Netherlands for the introduction of Periodical Inspections of ultrafine particles, followed by Belgium and Germany


Abstract: Modern diesel cars are equipped with very good emission control systems, so that emissions are kept to a minimum. These systems are very effective when they work properly. However, if something is wrong with this system, problems arise: Repairing it is quite expensive. Vehicle owners look for solutions and are tempted to adopt cheap solutions. As a result, the emissions are again old-fashioned high. No problem, you think: there is still a periodic inspection. But... At the moment there is no suitable method to determine that the vehicle has been tampered with and it simply passes the inspection. This will soon change in Belgium, Germany and the Netherlands: particle measurement will be introduced in these countries.
H.Peeters Weem /RDW, Netherlands 

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Repair and Replace – the VERT aftersale logistics expertise
K. Schrewe / HJS Emission Technology, Germany

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NPTI/PN measurements in JRC
A. MELAS / JRC, Italy

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