Air quality in urban environments has become a central issue of our present society as it affects the health and lives of the population all over the world. The first step in mitigating negative effects is proper measurement of the pollution level. This work presents a portable air pollution measurement system, built from off-the-shelf devices, that is designed to assure user privacy and data authenticity. Data is collected from sensor modules that can be hand carried or installed on vehicles, possibly leading to a vehicular sensor network that may cover a larger area. The main challenge is to provide authenticity for the sensor data while also ensuring user privacy. The proposed system assures authenticity and non-repudiation for the collected data by using group signatures and a blockchain-like structure for secure storage. We use regular key-exchange protocols based on elliptic curve cryptography in order to securely bootstrap a session key, then we benefit from secure tunneling to export data from sensors to the remote server. Post-update tampering is prevented by the use of a blockchain-like structure on the data server. We carry experiments both to determine the computational requirements of the procedures, as well as to measure indicators of air quality on nearby areas.

Counteracting the effects of air quality degradation is one of the main challenges in large cities today. To achieve such a goal, the first step is to control the emissions of various pollutant gases which in turn requires their concentrations to be measured such that proper methods can be applied. In this work we present a low cost urban air pollution monitoring system which we developed as proof-of-concept in Timisoara, Romania. The proposed solution is a Vehicular Sensor Network (VSN), with affordable midclass sensor nodes being installed on moving vehicles, ideally on the public transportation busses. The system measures temperature, humidity, the concentration of CO2 and dust, along with Volatile Organic Compounds (VOC). The aim of collecting weather data is to build correlations between air pollution levels and different weather conditions. In addition to technical constraints for measuring air quality, one of the challenges that we address is to implement secure transmissions between the devices. This raises several difficulties on microcontrollers that we use due to their low memory and computational resources. To answer both privacy and security issues, the proposed data transmission protocol of the measuring system, builds upon a modified version of the Station to Station (STS) protocol which allows secure tunnelling in an anonymous manner.