Louise Francis and María Alonso, Mapping for Change, CIC, University College London (UCL)


One of the air pollutants that is most present in our cities is nitrogen dioxide (NO2), which is emitted mostly from vehicle exhaust pipes. Air quality sensors are generally fitted in places that we may not come across on a daily basis. Diffusion tubes are a simple and reliable alternative for finding out what the air quality is like on our streets.


Measure the monthly concentration of NO2 in the air
Identify areas with better or worse air quality


  • 1 ‘Nitrogen Dioxide 20% TEA/Water’ diffusion tube to measure NO2. The cost of this tube includes a chemical analysis (contact: http://www.4sfera.com)
  • 1 tube holder
  • 1 cable tie or a cable
  • 1 sampling form
  • 1 pencil or pen
  • 1 map of the area to be explored
  • 1 bag with an airtight seal (zip)

Steps to follow


DECIDE on a good site to locate the diffusion tube

If you are going to measure the air quality with multiple tubes, DIVIDE the area so that the tubes are around 100m apart from each other


SET UP the tube in the tube holder, with the white lid facing down


USE a cable tie/cable to attach it to the chosen post, streetlight or traffic light (if it is on a public street, position it at a height of 2 to 2.5m)


LOCATE the tube in a site that allows for free air circulation around it, and at least 10 metres away from air outlets or ventilators


REMOVE the white lid for the tube so that the bottom side is open and exposed for 4 weeks


HOLD ON to the white lid so that you can close the tube again when you collect it


FILL in the sample form with the

- Date
- Time
- Height
- Precise location on the map
- Tube reference number
- Any other information


When 4 weeks have passed since you set it up, COLLECT the tube or set of tubes and immediately put the white lid back on the bottom end


WRITE DOWN the date and time when you collect the tube on the sample form, as well as any other information that may affect the results (e.g. the presence of insects, moisture or dirt, loss, etc.)


SEND it to the laboratory for it to be analysed


Les teves dades s'han enviat correctament.

Moltes gràcies!

Formulari incorrecte, revisa els camps en vermell




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