Browsing by Subject "O3"

The aim of this thesis is to understand how restrictions and recommendations to limit the spread of Covid-19 pandemic affected air quality in Helsinki from January to September 2020 and examine the health benefits coming from the decreased pollutant levels. During that time many restrictions to people’s movements took place. This caused a decrease in traffic rates which in turn affected air quality. The air pollutants included in this study are nitrogen oxide (NOx), tropospheric ozone (O3) and particulate matter (PM2.5 and PM10). The data was uploaded from SMEAR III -station in Kumpula neighborhood and the results were obtained by comparing concentrations from 2020 to those of 2018-2019. The data were divided into three periods, which were studied separately. The first period was the time before the lockdown (1.1.-17.3.), 2nd period was during the lockdown (18.3.-15.6.), and the 3rd period was after the lockdown (16.6.-30.9.). In addition, the health effects caused by the changes in pollutant concentration were studied with a calculator for financial benefits of emission reductions made by Finnish Environment Institute. The change in NOx concentrations during 2020 compared to 2018-2019 were -36.4 % in 1st period, -26.5 % in 2nd period and +34.1 % in 3rd period. The changes for O3 were +4.8 % (1st period), -8.6 % (2nd period) and -11.6 % (3rd period). PM2.5 concentrations changed -39.4 % (2nd period) and 0.0 % (3rd period) and PM10 concentrations -46.9 % (2nd period) and -14.7 % (3rd period) during 2020 compared to 2018-2019. Decrease of NOx in 1st period caused 2 600 t€/y savings in costs of air pollution related health effects. The changes in PM2.5 and NOx generated savings of 38 000 t€/y during 2nd period and -2 400 t€/y during 3rd period. Even though the pollutant concentrations decreased in most periods, the decrease can’t be explained only by changes in traffic rates and human activities. Other factors contribute air pollutant levels as well, including atypical weather during 2020. The study could be continued by separating the effects of weather, traffic and other contributing factors in changes in air pollutant concentrations.