Just one year ago, the CurieuzeNeuzen project presented its measurement results. After extensive research on these many data, it appears that moving from the city in search of clean air and then commuting back to that city, is of little benefit. Scientists conclude: "Certainly those who are in traffic for a long time have an increased exposure to air pollution".
Citizen Science project CurieuzeNeuzen Vlaanderen provides new insights into actual exposure
In May 2018, the University of Antwerp, together with the Flemish Environment Agency (Vlaamse Milieumaatschappij - VMM) and De Standaard, organised the largest citizen science project on air quality ever. 20,000 motivated citizens turned out to be researchers and measured the concentration of nitrogen dioxide on their homes’ facade. This resulted in an extensive - and internationally unique - dataset on traffic-related air pollution. On 24 September 2018, the measurement results were published and a detailed air quality map for Flanders was presented. This led to discussions at the kitchen table as well as questions in the city council and the parliament.
Dynamic vs static exposure
In recent months, the researchers have been diving even deeper into the project data. Scientists from UHasselt and HIVA have focused on the traveling behaviour of 5,000 participating citizen scientists, in order to be able to estimate the NO2 exposure during the day more accurately. After all, the CurieuzeNeuzen measurement itself only applies to the concentration at home, and nothing about when you are at work, at school, or commuting. This analysis shows that for an average Flemish person, 57% of the exposure takes place at home, 37% at the destination (usually the workplace) and 6% during travel.
"This newly calculated exposure is called dynamic exposure, as opposed to the concentration at the facade, which we call static exposure," explains Evi Dons (UHasselt). "The dynamic exposure is on average slightly higher than the static exposure: 24.1 versus 22.8 µg/m³. There are two main reasons for this. Worksplaces are often located in places with poorer air quality, for example in a city centre or near busy access roads. In addition, we are exposed to elevated concentrations of NO2 on our way to work: longer journeys therefore often also mean higher dynamic exposure.
Gap smaller than expected
The results show that the gap between people living and working in the city and commuters coming to the city is smaller than the CurieuzeNeuzen map suggests. "According to the analyses, inhabitants of the city of Antwerp who also work there have an average concentration of 33.7 µg/m³ at the front door, and a slightly lower dynamic exposure of 33.2 µg/m³", says researcher Sam De Craemer (UAntwerp). "Commuters from outside Antwerp, who come to work in the city, have on average a lower concentration of 23.6 µg/m³ at the front door, but a significantly higher dynamic exposure of 27.5 µg/m³.
In other words, the CurieuzeNeuzen map shows that the average difference in static exposure between living in and outside the city of Antwerp is 10.1 µg/m³. If the dynamic exposure is taken into account, the difference between resident and commuter is only 5.7 µg/m³. For Ghent, this difference decreases from 6.1 to 3.6 µg/m³. "So there is still a difference, but the gain that can be made by living outside the city is smaller than expected, if one still has to commute to a workplace with elevated concentrations.
Air quality is also more than just NO2. "Other pollutants and other sources outside of traffic also play a role," says Prof. Filip Meysman (UAntwerp and coordinator of CurieuzeNeuzen Vlaanderen). "Someone who leaves the city because of the NO2 concentrations and goes 'outdoors' to live next to a neighbour who burns wood, will see an increase in their exposure to fine particulate matter, and thus loses the small health gain in terms of NO2 ".
Flanders’ model maps are reliable
Scientists from VMM, VITO and UAntwerp also examined the reliability of the air quality maps used by the Flemish government. These maps are based on the ATMO-Street air quality model, developed by VITO. This model is used, among other things, in the BelAIR app. Meysman: "Thanks to the 20,000 measuring points of the CurieuzeNeuzen project, we were able to thoroughly test the ATMO-Street model, and an improved version is now available. Predicting the air quality using computer models is not easy, but in general we can say that the model maps used are reliable. This is important, because this ATMO-Street model also forms the basis for the air quality policy at the Flemish and local levels. We are pleased that with CurieuzeNeuzen we have been able to contribute to this."
Societal impact of CurieuzeNeuzen
The CurieuzeNeuzen project is still ongoing. At the end of November, the research results on the societal impact will follow. Among other things, it will be investigated whether CurieuzeNeuzen has influenced the behaviour of the participants, and whether the project has had an impact on the policy of local and regional authorities.
Links reports
Exposure commuting: https://www.vmm.be/publicaties
Control model maps: https://vito.be/nl/product/atmosys-luchtkwaliteitsmanagement-systeem#curieuzeneuzen
Press contact dynamic exposure
Evi Dons (not available on October 18) +32 494 35 57 33 evi.dons@uhasselt.be
Sam De Craemer +32 476 38 90 27 sam.decraemer@uantwerpen.be
Press contact ATMO-Street model and model maps
Wouter Lefebvre (VITO) +32 14 33 67 48 wouter.lefebvre@vito.be
General Press contact CurieuzeNeuzen
Filip Meysman +32 494 06 432 27 filip.meysman@uantwerpen.be
