In 2022, together with 14 partner organisations across Europe, ECAS implemented the first-ever transnational crowdsourcing on the topic of ‘air quality’. Citizens in 10 different cities were called upon to identify their issues with air pollution and propose policy solutions to their decision-makers at local, national and European level. Thousands of people joined the one-year crowdsourcing platform to give their contributions which ultimately led to 10 main recommendations co-created with the EEB and brought to the EU policy-makers. We also developed an Assessment Framework for E-Participation which was used to evaluate the whole process and led to 15 recommendations for crowdsourcing at the EU level.