Frequently asked questions about CurieuzenAir

CurieuzenAirs measured the air quality in their street for four weeks, from 25 September to 23 October 2021. However, air quality varies over time and will be different in summer than in winter. These differences were taken into account when calculating the CurieuzenAir results. By combining the continuous measurements taken at the stations of Brussels Environment and the European Parliament with the CurieuzenAir measurement tubes, the CurieuzenAir results give a good picture of the average concentration in 2021. The CurieuzenAir results would therefore have been exactly the same if the measurements had been taken in a different season.

The CurieuzenAir results show that air quality is very good in the vicinity of forests and parks. There are two main reasons for this. Firstly, trees can absorb NO₂ from the air and thus purify the air. The second reason is rather indirect. In forests and parks, NO₂ emissions are often low or even zero because traffic is kept away from them. The air quality is therefore automatically better because there are fewer sources of pollution in the immediate vicinity.

Just like CurieuzenAir, Les Chercheurs d’Air measured the concentration of NO₂ in Brussels. Les Chercheurs d’Air monitored NO₂ concentrations at 134 locations in Brussels for a whole year. The two citizen surveys are therefore very complementary. By taking measurements for a year, Les Chercheurs d’Air was able to map the variation of NO₂ concentration over time. CurieuzenAir focused on a short measurement period of four weeks but carried out measurements at 3.000 sites throughout the Brussels region. This allows us to identify differences between municipalities, neighbourhoods and even streets. Furthermore, the CurieuzenAir dataset allows us to estimate the NO₂ concentrations to which all inhabitants of Brussels are exposed.

The results obtained by Les Chercheur d’Air and CurieuzenAir are very similar. For example, in both studies, the European standard for NO₂ was exceeded in about 1.5% of the measurement points. The average NO₂ concentrations were also very similar: 23 µg m3 in Les Chercheur d’Air and 24 µg m3 in CurieuzenAir.

Although we cannot share all data due to privacy regulations, the coordinates of the measurement locations and the measurement results are available. Would you like to dive deeper into the data? Please contact us at info@curieuzenair.brussels.

Air quality is not the same everywhere. The results from CurieuzenAir show large differences in air pollution between the various municipalities in the Brussels Region. The highest values were measured at the level of the inner ring road (City of Brussels) and were up to ten times higher than the lowest NO₂ concentrations measured in the Sonian Forest. Curious about the average values in your municipality? Take a look at the scientific report (Supplementary Table 1 on page 47).

A result that differs from your expectations can have various causes. CurieuzenAir confirms that air quality in Brussels has improved considerably in recent years. The exceedance level (i.e. the percentage of sites exceeding the EU limit value of 40 μg m-3) is only 1.4% in 2021, which is low when put into historical perspective.

An other important note is that the CurieuzenAir measurement of NO₂ only provides information on air pollution related to traffic.

The effect of domestic heating and wood-burning on air quality is not properly reflected in our measurements. This is because these are primarily sources of fine particulates and less of NO₂. Fine dust could not be measured in this project. A CurieuzenAir measurement in a low-traffic area where a lot of wood is burned will therefore probably give a low measurement result.

For a limited number of measuring points, the measurement did not produce a reliable result. This may have several causes. Sometimes spiders or snails have nested in the tubes, a number of times we only received one tube in return and very occasionally something went wrong during the analysis of the measuring tubes in the laboratory. This was the case for 8.5% of the measuring points. Considering the scale of this study, this is a small percentage.

Important to know is that every participation is important in this large-scale research! Every point helped make this study possible and helped put air quality on the agenda in Brussels.

On the dot map at one of our media partners – De Standaard, Le Soir and BRUZZ – you can see the other results in your neighbourhood. That way you are informed about the measured air quality in your immediate vicinity.

CurieuzenAir has mapped the concentration of NO₂ in the Brussels-Capital Region. We focus on NO₂ because it is a key indicator of traffic-related air pollution, the high concentrations of which can have serious consequences for our health. But air quality is not just about NO₂. Other types of air pollution, such as particulate matter, deserve to be mapped. Other citizen science projects such as Luchtpijp (Air Pipe) offer you the opportunity to build your own fine particle sensor and measure the concentration continuously.

The CurieuzenAir map shows the measured NO₂ concentration at the location where the measuring frame was hung. If the house (and measurement frame) are at a large distance from the road, this can have an effect on the measurement result. This is because air quality improves considerably as your distance from the source of the pollution increases. To protect the privacy of all CurieuzenAirs, we cannot disclose the exact location of the measuring frame.

A number of articles are freely available from our media partners Le Soir, De Standaard and BRUZZ. In these articles you will find all the information you need to read and understand the map correctly. Do you want to know more about air quality in Brussels and be able to talk in detail about the research with your friends, family and neighbours? Be sure to check out the +Articles! When you register online with your e-mail address, you can often read the first few articles for free. You can also subscribe, or buy the printed De Standaard and Le Soir on Saturday 19 March. There you will also find all relevant articles and in depth analyses.

No follow-up CurieuzenAir research is planned at present. If you would like to start measuring the air quality in your street yourself, you can obtain information from Buro Blauw. They work with the same measuring tubes that are used in CurieuzenAir.

A high measurement result in your street is no reason to move. We spend only a third of our time at home. The air quality in your street is therefore only partly responsible for your total daily exposure. Your total daily exposure to NO₂ is the sum of the air you breathe at home, on the way to work, while sitting at school, or while exercising.

The CurieuzenAir map shows the measured NO₂ concentration at the location where the measurement board was hung. In selecting the CurieuzenAir sites, preference was given to places where air quality could be measured on the first or second floor. However, measurements sometimes took place on a higher floor. Because air quality improves greatly when the distance from the source of pollution increases, this can have an effect on the measured NO₂ concentration. When you click on a point on the CurieuzenAir map, you will therefore get more information about the floor where the measurement was performed

It may be that the data is incorrectly coded or that the person providing the street information has made a mistake. Please let us know using this form.

In September 2021, the WHO issued new recommendations for a lower health limit. Following this change, we have decided to adjust our scale to better reflect this latest WHO research. The colour scale is only adjusted for places with high NO₂ concentrations.

We are convinced that you can solve this problem in a creative way! Take a post-it or a large marker and mark your result. This way, the result of your measurement will stand out even more.

You can download a new poster here.

On 21 September 2021, participants could pick up their measurement kit at a DPD pickup point. The measuring campaign started on 25 September and lasted four weeks, until 23 October 2021. In March 2022 participants will receive their personal results by e-mail. From then on, you will find the results of all of Brussels on the interactive dot map on the websites of Le Soir, De Standaard and BRUZZ.

The measurement was carried out using a simple measuring device: participants attached (glued) an estate agent panel to the outside of a window, with two measuring tubes in the ‘nose’ of the panel. This panel was left in place for 4 weeks in October 2021. On the last day of the measurements, Saturday 23 October 2021, the two measuring tubes were taken back to a DPD collection point. The tubes were then analysed in the laboratory. The results will be published on 18 March 2022.

Participants will measure the air quality in their street with a simple measuring device: a v-shaped real estate panel attached (with glue) to the window. Two small sensor tubes are attached to the “nose” of the real estate panel. This sign will remain in place for 4 weeks and requires no maintenance or handling once attached. On the last day, Saturday 23 October, you will return the two sensor tubes to the same DPD Pickup point nearby.