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Using Smart Citizen Kits to track COVID-19 effect on pollution

Hi everyone!

First of all, we hope that you are all doing good given the current situation.
We just wanted to share with you that last week we published a little analysis of the effect of COVID-19 lockdown on pollution with open data from the kits deployed around Barcelona. We also included some other kits and we are cooking a bigger analysis, but for starters this is it:

The code that generated this is also open and can be accessed in this github repo.

We see this moment is an exceptional worldwide experiment and an opportunity for change and we would like to hear from you and see how things are evolving in other parts of the world. Have you seen changes in the data from your sensors? Are you planning on measuring something yourselves to see how this period affects the environment?

Hope you like it and looking forward!


That’s a really great article. Its such a pity we see so few kits in my part of the world. (Australia and Asia more generally)

Hi all!

In our twitter account (@fumutsrosolano) we have also been using the sensor to communicate the COVID effects on pollution in our neighbourhood. But while the noise data logically correlates with confinement periods, we have the opposite for PM2,5: higher concentrations during confinement and OK levels the last weeks (when activity and cars have returned to the street).

Anyone has thoughts on why is this happening in our case? Specially @oscgonfer and rest of the team in Barcelona.


Some thoughts.
Firstly are you kit(s) indoor or outdoor ?
If they are indoor, cv19 confinement will correlate with people choosing to cook meals at home. I have found my own PM x levels increase at meal times. TVOC also increases for same reason.

If they are outdoor and its winter then people using wood burning fires to heat homes (because they are at home) will cause increase in particulates. Even in summer they might light fireplaces at night because its cosier.

In summer time it might be that people < shock horror > might be burning garden vegetative waste, generated because people spend time tidying their garden when confined at home.
In some places in the world summer coincides with increase in particulates as people burn farmland vegetation and undergrowth.

These suggestions might not work where you are but maybe it will help generate some ideas for you…


Greetings from la Garrotxa,

I think that we need to take into account other factors such as rain, wind, etc. during previous days that may have altered a nice looking drop in air pollution. I looks more logical when you see CO2eq instead of PM2.5.


Thank you both @bryn.parrott and @doktorkampi for your time and answers!

@bryn.parrott: our kit is outdoors, located in a very dense historic neighbourhood with narrow streets (8 m aprox.) and mainly condominiums (no gardens or fireplaces). So even if your hints could be useful in other contexts, cannot explain this situation. Thanks anyway! :slight_smile:

@doktorkampi: yes, I guess weather is the answer. April was an specially rainy month in Barcelona this year, so it could be wind from the Sahara that influenced the measurements…
Regarding CO2eq, I’ve never payed much attention to this variable, since I had read somewhere in the manuals, that it was not such an accurate tool… Am I wrong? According to your experience, do you actually use it in order to assess pollution? I usually rely on the PM2,5 values, but it could maybe also be an interesting variable to communicate to people


Hi Xavi,

In my opinion, CO2eq is not a good parameter to assess air quality in terms of human health, but an indirect indicator of greenhouse gases emissions, which at the end may be harming our planet and therefore our species. When we look at PM2.5 we can easily correlate to a particular level of air pollution that we breathe, whereas CO2eq may indicate the amount of certain emitted pollutants. In this particular case, we observed a sustained decrease in CO2eq after the lockdown in Olot, but particulate matter was harder to correlate to regular activities that may pollute such as road traffic.

Hope that this helps.



It’s really nice to see that you are getting to these conclusions. This article talks about the effects of weather conditions in a study using SCKs carried out in Bologna (similar weather as Barcelona with some differences in winters). If you refer to pages 14-15 the discussion about these topics is explained, and the results in April could be somehow explained, keeping in mind that we have not used the SCKs in the same controlled way as this study, as we do not know the exact exposure for each device.

With respect to CO2eq, consider it a proxy to volatile organic compounds (CO2eq and tVOC are the same), and mostly indicate as @doktorkampi says, human activity that puts in the atmosphere substances that contain highly volatile substances such as solvents, paints,… Is it a definite measurement? No. However, it can be used with other variables (T, H, PM…) to understand trends in the data.