Development of air quality boxes based on low-cost sensor technology

Analyses of the relationships between climate, air substances and health usually concentrate on urban environments due to increased urban temperatures, high levels of air pollution and the exposure of a large number of people compared to rural environments. Ongoing urbanization, demographic aging and climate change lead to an increased vulnerability with respect to climate-related extremes and air pollution. However, systematic analyses of the specific local-scale characteristics of health-relevant atmospheric conditions and compositions in urban environments are still scarce due to the lack of high-resolution monitoring networks. In recent years low-cost sensors became available, which potentially provide the opportunity to monitor atmospheric conditions with a high spatial resolution and which allow monitoring directly at exposed people.

We develop a measurement system for several air substances like ozone, nitrogen oxides, carbon monoxide and particulate matter as well as meteorological variables like temperature and relative humidity, based on low-cost sensors. This involves the assembly of compact, weatherproof boxes with 3D-printed parts. They contain a control unit based on Arduino hardware to gather the sensor data as well as self-designed printed circuit boards (PCBs). A Pycom microcontroller is used for low-power, high-temporal data transmissions by Long-Term Evolution Cat-M1 (LTE-M). These Atmospheric Exposure Low-cost Monitoring units (AELCM) include digital and analogue sensors for air substances and meteorological variables, LCD display, RTC module, uninterruptible power supply, active ventilation, a SD Module as a data black box in addition to an optional internally running FTP server and optional GPS module. A computational fluid dynamics (CFD) simulation is used to evaluate the air flow inside the AELCM units. Sensors are selected based on own analyses as well as according to evaluation and performance in other projects. The measurement equipment is extensively tested using the high-quality measurement unit for meteorology and air substances (Atmospheric Exposure Monitoring System, AEMS) of our research group, located at the Augsburg University Hospital.