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Sensor network improves understanding of spatial distribution of particulate matter

Sensor network improves understanding of spatial distribution of particulate matter

Particulate matter concentrations in busy streets can be fairly high compared to their respective urban background concentrations.

Finnish Meteorological Institute measured particulate matter (PM) concentrations together with Tampere University, Helsinki Region Environmental Services Authority (HSY), and Pegasor Oy at four different stations in Helsinki Metropolitan Area. Two of the stations represented residential areas in Rekola, Vantaa and two of the stations represented busy street canyon site at Mäkelänkatu, Helsinki and an urban background area at Kallio. The measurements were conducted with a Pegasor developed AQ Urban monitor which is specifically applicable to the measurement of lung deposited surface area (LDSA) of ultrafine particles (diameter 10–400 nm).

Based on the results, the dynamic variations and concentration levels of LDSA exhibited clearly different characteristics in the different measurement sites. Concentration levels at the street canyon station were twice as high when compared to the background station. The difference was largely explained by the adjacent vehicular traffic, which emits mainly ultrafine particles. Furthermore, the concentration levels at the street canyon site were highly dependent on the hour of day.

Long-term LDSA averages at the two residential area stations where similar, although significant differences could be observed at some evenings. The distance between the two stations was only 670 meters which indicates that a local source was causing the difference. Highest concentrations levels were typically observed in the evenings when residential wood combustion was occurring.

The results obtained from this study underline the importance of spatially extensive measurements. Particularly in large cities, several different local sources may be present simultaneously within a relatively small area. Therefore, a single measurement point may not be representative of the whole area. Sensors may provide a cost-efficient way to spatially extend the measurement coverage, and thus gain more comprehensive understanding of the city-scale PM dynamics.

Further information:

researcher Joel Kuula, Finnish Meteorological Institute, tel. +358 44 722 7718,

Kuula J., Kuuluvainen H., Niemi J. V., Saukko E., Portin H., Kousa A., Aurela M., Rönkkö T. and Timonen H. 2019. Long-term sensor measurements of lung deposited surface area of particles emitted from local vehicular and wood combustion sources. Aerosol Science and Technology.

The study was funded by Academy of Finland (MISU program/PARMAT; Particulate matter in mines and mining environments –project 297804), Business Finland (Cityzer; Services for effective decision making and environmental resilience), Regional Innovations and experimentations fund AIKO, governed by the Helsinki Regional Council (project HAQT; Helsinki Air Quality Testbed, AIKO014), and by European Regional Development Fund, Urban innovative actions initiative (HOPE; Healthy Outdoor Premises for Everyone, project no: UIA03-240).

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