The paper presents the results of a 1.5-year evaluation study of low- and medium-cost ozone sensors. The tests covered electrochemical sensors: SensoriC O3 3E 1 (City Technology) and semiconductor gas sensors: SM50 OZU (Aeroqual), SP3-61-00 (FIS) and MQ131 (Winsen). Three copies of each sensor were enclosed in a measurement box and placed near the reference analyser (MLU 400). In the case of SensoriC O3 3E 1 sensors, the R² values for the 1-h data were above 0.90 for the first 9 months of deployment, but a performance deterioration was observed in the subsequent months (R² ≈ 0.6), due to sensor ageing processes. High linear relationships were observed for the SM50 devices (R² > 0.94), but some periodic data offsets were reported, making regular checking and recalibration necessary. Power-law functions were used in the case of SP3-61-00 (R² = 0.6–0.7) and MQ131 (R² = 0.4–0.7). Improvements in the fittings were observed for models that included temperature and relative humidity data. In the case of SP3-61-00, the R² values increased to above 0.82, while for MQ131 they increased to above 0.86. The study also showed that the measurement uncertainty of tested sensors meets the EU Directive 2008/50/EC requirements for indicative measurements and, in some cases, even for fixed measurements.

Urban beekeeping has become increasingly popular, despite having different objectives than the large-scale professional/commercial one. Not so much focused on financial profit, urban apiculture provides valuable educational opportunities, promotes the greening of cities, and creates environmental awareness. Many companies and institutions make it a valuable component of their public relations strategy. Urban beekeeping benefits may be enhanced by applying specialized technical infrastructure. In particular, the use of modern technologies attracts the younger generation to be involved in beekeeping. This paper aims to present the abilities of the automatic monitoring system, which meets the goals of urban beekeeping. The set of equipment consists of a sensor module, video cameras, a unit for data acquisition, and a system for data transmission, presentation, and visualization. The monitoring system allows for real-time observation of the beehive interior and entrance. It continuously measures selected physical and chemical parameters of the beehive atmosphere and provides a record of the beehive’s weight. Additionally, ambient air is monitored for reference. The video streaming and measurement results are available to the public online through the dedicated webpage. System performance was evaluated regarding the interactions with honey bees, sensor measurement characteristics, and data collection efficiency. Three months of operation in the urban apiary confirmed that the system is fully functional and fulfills its objectives. System development continues.