Measurements reveal that a gap has existed between official European emissions standards for vehicles and their actual emissions on the road for some time now. We have been measuring emissions of hazardous substances such as nitrogen oxides (NOx), particulate matter and CO2 by private and commercial vehicles, ships and trains under real-world conditions for many years. We feed the results into our models to be able to predict the development of air quality.

This enables us to help government agencies, non-government bodies and users to make decisions to improve air quality based on factual data.

Precise measurements of real-world emissions

We conduct most of our real-world measurements using the Portable Emission Measurement System (PEMS) and the smart version of the system, called Smart Emission Measurement System (SEMS), which we developed in-house. We use these systems to conduct daily measurements of both emissions and driving behaviour. Thanks to this data, we have access to accurate real-time information on emissions in all conceivable situations and over long periods of time.

The data makes an important contribution to understanding the conditions under which harmful emissions and CO2 production are at their highest (or lowest). We use this knowledge to advise government agencies on how to improve air quality through source-based policies, such as European emissions legislation, national incentives, local environmental zones and traffic management measures. NGOs and environmental organizations use our measurement data too.

Technology, driving behaviour and legislation

We compile an accurate picture of real-world emissions based on sources, relationships, vehicle technology, driving behaviour, legislation and the conditions under which hazardous emissions are produced. We also gather the same data on ships and mobile machines. This information reveals which vehicles are cleaner than others and under which conditions, and we can also provide recommendations on changing driving behaviour. Our recommendations on which buses to use as part of inner-city public transport tenders have had a major impact on local air quality.

Advice to consumers and manufacturers

The next step is to monitor much larger numbers of vehicles using relatively simple measuring devices such as SEMS. Owners of fleets of vehicles (such as government agencies, businesses and lease companies) and consumers can have our measuring devices installed in their vehicles. These enable us to gather vast quantities of measurement data on various types of private and commercial vehicles and under a wide range of conditions. This drastically increases the amount of information in our database and so improves the models with which we predict emissions and calculate scenarios for the future.

In the future, we will be able to tell individual consumers precisely which vehicles are the cleanest and most efficient under normal real-world conditions, and how they can influence this with their driving behaviour. Vehicle manufactures can use our data to optimize their emission reduction systems.

Real-time insights obtained from various sources

We can use data obtained from sensors in cities and along motorways which are integrated in roads, traffic lights, cameras and the latest vehicles to provide visual and real-time information on congestion, traffic flows, noise pollution and emissions of hazardous substances. Municipalities can use our Urban Dashboard to gain continuous and real-time insight into all factors that influence air quality, which can be predicted based on simulations of traffic management measures or the implementation of environmental zones.


Download the full 2022 report

Detecting high NOx emissions of aged petrol cars during the periodic technical inspection


Addressing elevated vehicle emissions in Flanders

08 June 2021
A novel study for the Flemish Environmental Agency on vehicle emissions has been carried out by TNO, together with partners Vrije Universiteit Brussel in Belgium and, in part, HEAT in the USA. In the... Read more