National project · Air quality
Vigilantes del Aire
Citizen science to measure air quality with strawberry plants
About the project
Vigilantes del Aire (‘Air Watchers’) was a citizen science project to find out about air quality in towns and cities across Spain. It used strawberry plants as biosensors: small measuring stations looked after by the participants themselves.
Each participant placed a potted strawberry plant outside their home (on a window sill, balcony or terrace) and looked after it for about two months. They then posted a few leaves to be analysed in the laboratory. No prior knowledge or technology was needed to take part.
In the laboratory, the team measured the magnetic properties (SIRM) of the metallic pollution built up on the strawberry leaves (Fragaria vesca L.), which serve as an indicator of air pollution.
In the 2020 edition, 5,790 plants were handed out in urban and rural areas of Spain, including cities such as Madrid, Barcelona, Zaragoza, Bilbao, Vitoria-Gasteiz, Granada, Girona, Castellón, Burgos, Pontevedra, Torrelavega and Algeciras. A total of 2,755 samples came back, of which 2,465 were suitable for analysis: a return rate of over 48%.
In 2023 the project reached more than 90 schools in Madrid, in an edition organised by Madrid City Council in which hundreds of pupils measured air quality with their plants.
Ibercivis had previously used the same method in Zaragoza with Vigilantes del Cierzo, with editions in 2016–2017 and 2019.
Project objectives
- Produce an air quality map of Spain using strawberry plants as measuring stations.
- Measure the concentration of heavy metals built up on the leaves as an indicator of pollution.
- Make citizen science accessible to everyone, whatever their age or background.
- Involve as many people as possible in data collection.
The role of Ibercivis
Ibercivis launched and coordinated the project: it organised the distribution of plants, supported participants throughout the experiment, received the samples and published the scientific results. It worked with the University Institute for Environmental Sciences at the University of Zaragoza and with Daniel Bruno, a researcher at the Pyrenean Institute of Ecology.
Our activities
- Distribution of potted strawberry plants with an instruction kit, through a network of regional ambassadors in the 2020 edition.
- Collection of leaf samples by post and their analysis.
- Publication of the 2019 results (in Spanish), with an interactive map showing each location.
- Preparation of the 2020/2021 scientific report (in Spanish).
- An edition in Madrid schools (December 2022 to December 2023), with analysis of arsenic, cadmium, chromium and other elements, and publication of its results (in Spanish).
- An explainer video about the project (2021).
- Media coverage.
