Smart Citizen Kit and Station: An open environmental monitoring system for citizen participation and scientific experimentation

In the past years, multiple research projects have explored the potential of low-cost environmental sensors for urban air pollution monitoring. However, each project has taken its own independent and in many cases, fully or partially closed approach. We present the Smart Citizen System, a flexible, easy-to-use and fully open-source environmental monitoring solution for particulate matter, carbon monoxide, nitrogen dioxide, noise levels, and many other indicators. The use of low-cost sensors in recent years has been generally approached in two different ways citizen science and educational activities, where the primary purpose is to engage citizens in the measurement process and raise awareness of environmental concerns; and a more sophisticated scientific approach, where the main aim is to study the potentiality of the low-cost sensing technologies. The Smart Citizen System balances modularity with integration to fulfil both needs by providing an extendable solution, with different ranges of sensors based on the same core components. With that aim, two solutions have been developed: the Smart Citizen Kit, intended for citizen science and awareness activities; and the Smart Citizen Station, designed to serve as a more complex and accurate set of air pollution sensors. The design is based on the principle of reproducibility, also integrating non-hardware components such as a dedicated storage platform and a sensor analysis framework. The core system bases its sensing capabilities in widely reviewed low-cost sensors and aims to provide a robust framework for environmental monitoring activities. By making everything open, from the hardware to the software platform or the sensor post-processing algorithms, we hope others might find it useful as a development platform allowing them to focus on their project particular needs instead of reinventing everything from the ground-up