Air quality trends in Finland, 1994–2018

Abstract

In this thesis, long-term, multicomponent, high-resolution (time and accuracy) air quality monitoring data from about 400 sites across Finland since 1994 are integrated into a single unified and compact view to demonstrate past air quality development and to assess the reasons behind the development at the national level. This thesis demonstrates that internationally launched and nationally implemented regulatory controls have had an important role in improving air quality in Finland. The pollutants subject to long-term ambitious international abatement strategies (like SO2 and persistent organic pollutants) have decreased the most. Also, NOx emission control has been successful, but urban roadside NO2 concentrations have not decreased as expected. The increase in diesel cars (and their potentially high primary NO2 emissions) may have been one factor in slowing down the decline of concentrations. However, the development of emission reduction technologies together with the improved type approval test procedures have resulted in a reduction in the significance of primary NO2 emissions in Europe. In Finland, our relatively old car fleet and the increased import of old diesel cars cause uncertainty for future development. Due to the use of studded tyres and manifested as elevated concentrations of PM10, springtime street dust is a local air pollution problem. This thesis suggests that local abatement measures (e.g., reducing traffic, changes in the car fleet, road maintenance activities) have been moving in the right direction, and the springtime street dust levels have been reduced. Although air quality standards are not exceeded today, street dust remains a persistent flaw in our otherwise good air quality. In Finland, the ozone peak levels have been declining since 2006. Similar development has been detected in Europe and North America, and it is related to decreasing anthropogenic precursor emissions of NOx and VOCs. For Finland, high background concentrations are more problematic, and reducing them would require international and even hemispheric cooperation. The available long-term background data of PAH concentrations suggest that no widespread decrease in concentrations has occurred. This is not necessarily surprising as the major global sources are small-scale solid fuel combustion and wildfires. Efforts to reduce these emissions have been relatively limited or non-existent so far. Publishing unit Atmospheric Composition Research/Air Quality Classification (UDC) Keywords 502.3:613.15 (air quality) pollution, monitoring, data-analysis, 303.446.3 (time series study) time development, abatement ISSN and series title ISBN 0782-6117 978-952-336-101-0 (paperback) Finnish Meteorological Institute Contributions 978-952-336-102-7 (pdf) DOI Language Pages 10.35614/isbn.9789523361027 English 54 0782-6117 978-952-336-101-0 (paperback) Contributions 978-952-336-102-7 (pdf) DOI Kieli Sivumäärä 10.35614/isbn.9789523361027 englanti 54 Publications of the thesis This thesis consists of five original articles and a synthesis...

Added Value of Vaisala AQT530 Sensors as a Part of a Sensor Network for Comprehensive Air Quality Monitoring

“…Traffic volumes were clearly lower in 2020 due to Covid-19 restrictions, but official traffic estimates were not yet available. Concentrations of particulate matter (PM 2.5 and PM 10 ) and gaseous pollutants (NO x , O 3 , CO) are continuously monitored at the site (e.g., Anttila, 2020;Barreira et al, 2021). The air quality parameters were measured with the following reference instruments: PM 2.5 and PM 10 with Fidas 200 (Palas), NO x with APNA 370 (Horiba), O 3 with APOA 370 (Horiba), and CO with APMA 360 (Horiba).…”