Recent advancements in low-cost portable sensors for urban and indoor air quality monitoring

The spatiotemporal heterogeneity of the air pollutants complicates appropriate monitoring. The collective measures or crowdsensing is a promising approach to achieve a better air pollution assessment because it includes the local concentration of pollutants, as well as the position and mobility of people. Thus, compared to traditional static monitoring, the participatory sensing data by low-cost sensors can avoid the misclassification of exposition to air pollutants, enabling a comprehensive understanding of their health effects. This systematic review integrates each core part of what is required to achieve crowdsensing for air pollution: sensors, portable devices, and data models. Despite the limitations of sensors in terms of sensitivity and selectivity, it has been possible to use portable air monitors to determine pollution hotspots around the world. However, limited models for data processing, performance issues when using low-cost devices, in addition to lack of community engagement, are the challenges to overcome for the feasibility of air pollution assessment with portable monitors. Graphical abstract