The CurieuzeNeuzen citizen science project: large-scale air quality mapping of NO2

concentrations in Antwerp, Belgium

Joris Van den BosscheFilip Meysman

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Situating Antwerp

Tropospheric nitrogen dioxide (NO2) vertical column density (VCD). Data source IUP Heidelberg.

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Situating Antwerp

RIO-IFDM air quality model for NO2

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Situating Antwerp

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Situating Antwerp

RIO-IFDM-OSPM air quality model for NO2(VITO, http://opendata.antwerpen.be/datasets/luchtkwaliteitskaarten-no2)

The CurieuzeNeuzencitizen science project

“Nosy parker”

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Goals of the CurieuzeNeuzen project

Scientific

• Quantitatively map the street-to-street variation in air quality in a large city.

• Ground truthing for computer models of the dispersion of NO2 concentrations in the city.

Social

• Raising awareness of the importance of good urban air quality.

• Demonstrate that citizen science works: collect high qualitydataset.

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The CurieuzeNeuzen citizen science project

Elements of the successful campaign:

• Robust, simple measurement method

• Participation (partners, volunteers, participants)

• Scientific method: data quality control

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Measurement method: sensor choice is crucial

• Robust and simple sensors: Palmes diffusion tubes for nitrogen dioxide (NO2)

• Simple and standardized method to mount sensors to window: real-estate panel

• 4 week measurement in May 2016

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Partner organisations

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Team of volunteers

Arduino programmer

Graphical designer

Databasedeveloper

….Telecomspecialist

Datamining statistician

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Many participants

1840 families43 schools8 UA campus55 companies15 organizations10 hospitals35 parks and bridges

Participants: 2000

Recovery: 98%

Candidates: 2768

··· not selected

out of domain

selected

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2000 measurement location

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Data quality control

• Duplo measurements at each location

• Mean absolute difference of 1.14 µg/m³ (RMSE of 4.4%)

• Comparison between passive samplers and reference method

• During campaign in May 2016 at 8 monitoring stations

• Additional campaign in August 2016 at 6 monitoring stations

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Calibration and uncertainty of the measurements

• NO2 samplers systematically lower than reference measurements

• Linear response, but with offset

• After calibration, expanded uncertainty (16%) comparable tomeasurements GGD Amsterdam (13-27% for monthly data)

Results

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NO2 (microgram per m3)

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NO2 concentrations by district

NO2 concentration(microgram per m-3)

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Distribution of the concentrations

→ Driving factors: traffic, road type, distance to ring road, skyviewfactor, population density

NO2 concentration (microgram per m-3)

Bridges over the ringroad

Traffic-free zones, parks

Average36.4 µg/m³

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Influence traffic

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Urban NO2 island – impact ring road

• Inner city: 40 µg/m³• Outer city: 33 µg/m³

Inner city Outer city

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Comparison with model (RIO-IFDM-OSPM)

• Underestimation of the high concentrations

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Unexpected street canyons

ModelMeasurements

Sergeyselstraat

Kerkstraat

Osystraat

Borsbeekstraat

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Prognosis exceedance of the limit value

• Measurements in May: 5 to 15 % lower than yearly average => adjust limit value

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Prognosis exceedance limit value

• Adjusted limit value for May of 36 µg/m³

> 38 µg: 35%

45% of the measurement locations

> 34 µg: 61%

Conclusions

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Large outreach: participants, media coverage, …

But also valuable scientific project

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Conclusions

• Unique project, unique high-quality dataset

• Scientific:

• Passive samplers map street-to-street variation

• Insights to better model air quality

• Social

• Air quality still a problem: higher level of exceedances thanexpected

• Insights for policymakers to improve air quality

• Raised awareness through active participation and media coverage

Thank you for the attention

Thanks to all volunteers and participants!www.curieuzeneuzen.eu