An Optical Sampling System for Distributed Atmospheric Particulate Matter

The atmospheric particulate matter is considered one of the most dangerous pollutants because of its effects on the climate and human health. Particulate concentration changes largely with spatial position and time, and thus, a distributed real-time monitoring would be mandatory, especially in densely populated areas. The proposed optical sampling system has a negligible cost with respect to the already available instruments and can be used for deploying a capillary particulate monitoring network thanks to its wireless capability based on the LoRa protocol. The proposed solution employs an optical method for the atmospheric particulate detection and the estimation of its concentration and size distribution. The air is sampled by a small pump which forces a known flux through a commercial glass-fiber filter, where the particulate is captured. A low-cost digital camera coupled with a multi-wavelength lighting system takes periodical photographs of the filter surface, and a small PC-on-single-board processes the acquired images in order to identify the particles and to estimate their size. The system can work unattended for a long time and transmit remotely measurement data with a typical range of few kilometers.