Monitoring actual emissions: report summary

Sustainable traffic and transport

Measurements show that there is a gap between the European standards for motor vehicle emissions and the actual emissions on the road. For years, we have been measuring under real conditions the emission of harmful substances such as nitrogen oxides (NOx), particulates, and CO2 from passenger cars, vans and lorries, ships, and trains.

We fed the results into our models to predict air quality. This allows us to help governments, private parties, and users to make evidence-based decisions on improving air quality.

Accurately measuring emissions in practice

The measurements under real conditions are mainly done with the Portable Emission Measurement System (PEMS) and with the smart variant SEMS developed by TNO. This enables us to monitor emissions and driving behaviour on a daily basis. This data provides us with accurate, real-time data on emissions under all conceivable situations over an extended period of time.

The data is needed to understand under what conditions harmful emissions and CO2 emissions are high or low. With this knowledge, we can advise governments on how to improve air quality through source-based policy. For example, European emissions legislation, national incentive schemes, local environmental zones, and traffic measures. NGOs and environmental organisations also use our measurement data.

Advising consumers and manufacturers

We monitor large numbers of vehicles with relatively simple measuring devices such as SEMS. Owners of fleets of vehicles, both government agencies and companies (including lease companies), and private citizens can have our measuring equipment installed in their cars. This allows us to collect large quantities of measurement data on all types of passenger cars and delivery vans under various conditions. This means a great enrichment of our database and our calculation models with which we make emission forecasts and calculate future scenarios.

In the future, we will be able to tell individual consumers exactly which cars are actually clean and economical under normal use, and what driving behaviour contributes to this. We will be able to help vehicle manufacturers optimise the adjustment of the emission reduction system.

Emission factors for motorways and non-motorway roads to calculate air quality and nitrogen deposition

TNO publishes current data that are used to calculate emissions of environmental pollutants. These emission factors are used for the Standard Calculation Methods (SCM) 1 and 2 for air quality, and for determining nitrogen deposition with the help of the AERIUS calculation tool.

The Dutch government has an obligation to monitor air quality in the Netherlands annually. In addition, government agencies and companies have to determine the consequences of planned projects for air quality. To ensure that it always has the latest input data, the government has been updating air quality models annually since 2006 and publishes these by 15 March. Emission factors for nitrogen deposition, such as ammonia emission factors, are formally outside this obligation. There is considerable overlap between the two emission factors and TNO brings together both sets here with the latest input data.

Download here the emission factors for air quality as at 15 March 2022, and the 2022/2023 AERIUS release.

View our publications and reports

Download the 2022 report

Read more in the report 'Approaches for detecting high NOx emissions of aged petrol cars during the periodic technical inspection'.

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