In 2014, in connection with his doctoral research, Jelle Hofman (37) was a co-leader of AIRbezen, one of the first large-scale citizen science projects, in which strawberry plants on windowsills in Antwerp were used to investigate air quality. This formed the prelude to the well-known CurieuzeNeuzen project, in which VITO was one of the leading partners. Nowadays, Hofman is working at VITO himself. In his work within the organisation's healthy living environment domain, he is carrying out research into air quality monitoring in our surroundings. ‘It fascinates me how the measurements we take can make what is invisible visible.’ 

‘As far as PFAS monitoring is concerned, we're doing truly pioneering work’

From AIRbezen and CurieuzeNeuzen to PFAS: you've been involved in all of those. How did you get where you are today?

‘The AIRbezen project formed part of my doctoral research at the University of Antwerp, where, by utilising the biomagnetic properties of leaves, we were seeking to make new discoveries about the concentration and composition of fine particulate in the air. After obtaining my doctorate in 2014, I worked at the Public Waste Agency of Flanders (OVAM) for a while and later at the Flanders Environment Agency (VMM), where we were working to develop an innovative measurement network for the monitoring of ultrafine particulate in North-West Europe as part of the JOAQUIN project. 

In 2015, I went back into academic research. As a postdoc, I continued researching the topic that I had been working on until 2014. I compared the results of air quality measurements with models that were applied in urban environments such as street canyons. By carrying out measurements, I also investigated individuals' exposure to various pollutants and set out to determine the chemical composition of dust from various sources that can affect our health. 

Whereas in AIRbezen, we were still working with small plants and reference equipment, my postdoc research required me to make increasing use of innovative technologies, including portable measuring devices and sensors. They are what makes it possible to obtain high-resolution spatial data relating to air quality. It was as a result of this work that I came into contact with imec, which specialises in innovative sensors. I worked there for over two years, developing innovative sensor applications, calibration algorithms and interpolation models, during which I also made use of AI technologies. Amongst other things, we fitted 17 postboxes with sensors in order to chart the air quality in Antwerp in real time and in a highly detailed way. In August 2021, I then started work at VITO.’ 

And you're still involved in monitoring air quality.

‘Up to now, that has certainly been the common thread in my career. By using new and improved methods, we are endeavouring to gain an increasingly accurate view of the air quality in our environment. At VITO, we also make use of innovative sensor technology, but here, the monitoring itself is the main focus. VITO is Flanders' reference laboratory, after all. That does mean, however, that I am able to experience developments in my specialist field from a front-row seat. For example, we will soon be able to use ammonia and PFAS to measure an even wider range of pollutants. That is what excites me about my work and my research. It fascinates me how the measurements we take can make what is invisible visible.’

In the past few years, PFAS has also become a familiar concept in Flanders. What are you doing in order to monitor those substances?

‘The PFAS family includes over ten thousand different synthetic compounds, so in many cases, we need to make use of a variety of sampling and analytical methods. In collaboration with GOAL, we are developing a number of measurement methods that will enable us to sample and analyse PFAS in the air (in emissions, ambient air and discharges). In that regard, the work we are doing is genuinely pioneering on an international level. 

On 15 January, our new method that enables around 50 PFAS compounds to be measured in stack emissions was included in the new air quality measurement compendium (LUC). This is a first in Europe and forms a major step on the road towards more harmonised provisions governing PFAS in the air.  

We developed this method based on the methodology used by the American environment agency EPA and on our own practical experience in connection with the PFAS emissions measurements we have been carrying out since 2021 on various chimney stacks in Flanders.’

VITO's main campus is located in green surroundings in Mol, so the air quality there will be good, won't it?

‘That is certainly an important asset. Going out for a jog in a natural setting during the afternoon feels great. (Laughs) I'm also trying to motivate my colleagues to play sport together whenever we can.’

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