Early Warning Systems for COVID-19 Infections Based on Low-Cost Indoor Air-Quality Sensors and LPWANs. - Nikolaos Peladarinos; Vasileios Cheimaras; Dimitrios D. Piromalis; Konstantinos G. Arvanitis; Panagiotis Papageorgas; Nikolaos Monios; Ioannis Dogas; Milos Stojmenovic; Georgios Tsaramirsis (Sensors, 2021)