Simultaneous mobile PM10 monitoring provides high definition spatial and time localization of hotspots of poor air quality in an urban environment

Many cities suffer from poor air quality resulting from the accumulation of anthropogenic sources of air pollution, especially aerosol particles with an aerodynamic diameter smaller than 10 μm. The urban sources vary significantly in space and time, requiring temporal and spatial monitoring of air quality. Although becoming more common, mobile monitoring still rarely includes a large urban area. The aim was to carry out and analyze a large spatial and temporal monitoring of the variability in air quality in a large urban area in Prague 7. For this purpose, the area of interest was divided into six smaller sub-areas, where a simultaneous and repeated mobile PM10 monitoring was done. In the period from December 2019 to May 2020, a total of 174 walks, with a total length of 664 km, were carried out on 10 days. On most of these days, the average PM10 concentrations were below the 24-hour limit value (50 μg∙m−3), except for one day, which was a critical day for the whole of the city of Prague. The temporal variability in PM10 varied significantly with meteorological conditions, independent of location. The spatial variability in PM10 revealed that lower concentrations were always recorded in green urban areas and high concentrations in two types of hotspots, non-coincidental (regular traffic, residential heating) and coincidental (heavy vehicles, cigarette smoke). The method of collecting and evaluating the data allowed a high spatial and temporal PM10 distribution monitoring and can be used to identify anomalies occurring in urban areas and for other pollutants at different locations.