Comparison of concentrations of chemical species and emission sources PM2.5 before pandemic and during pandemic in Krakow, Poland.

Observations of air pollution in Krakow have shown that air quality has been improved during the last decade. In the presented study two factors affecting the physicochemical characteristic of PM2.5 fraction at AGH station in Krakow were observed. One is the ban of using solid fuels for heating purposes and the second is COVID-19 pandemic in Krakow. The PM2.5 fraction was collected during the whole year every 3rd day between 2nd March 2020 and 28th February 2021 at AGH station in Krakow. In total 110 PM2.5 fraction samples were collected. The chemical composition was determined for these samples. The elemental analysis was performed by energy dispersive X-ray fluorescence (EDXRF) technique, ions analysis was performed by ion chromatography (IC) and black carbon by optical method. In order to identify the emission sources the positive matrix factorization (PMF) was used. The results of such study were compared to similar analysis performed for PM2.5 for the period from June 2018 to May 2019 at AGH station in Krakow. The PM2.5 concentration dropped by 25% in 2020/2021 in comparison to 2018/2019 at this station. The concentrations of Si, K, Fe, Zn and Pb were lowering by 43-64% in the year 2020/2021 in comparison to 2018/2019. Cu, Mn, Zn and Pb come from mechanical abrasion of brakes and tires while Ti, Fe, Mn and Si are crustal species. They are the indicators of road dust (non-exhaust traffic source). Moreover, the annual average contribution of traffic/industrial/soil/construction work source was reduced in 2020/2021 in comparison to 2018/2019. As well the annual average contribution of fuels combustion was declining by 22% in 2020/2021 in comparison to 2018/2019. This study shows that the ban and lockdown, during COVID-19 pandemic, had significant impact on the characteristic of air pollution in Krakow.

Seasonal contribution of assessed sources to submicron and fine particulate matter in a Central European urban area.

This study presents the air pollution findings of the submicron (PM1) and fine (PM2.5) particulate matter. The submicron particles are entirely absorbed by the human body and they cause the greatest health risk. For the PM2.5 concentration, there are yearly and/or daily limit values regulations by the European Union (EU) and World Health Organization (WHO). There are no such regulations for PM1 but for health risk reason the knowledge of its concentration is important. This paper presents the seasonal concentration contribution of PM1 and PM2.5, their chemical composition and assessed three basic sources. Daily samples of both fractions were collected from 2nd July 2016 to 27th February 2017 in Krakow, Poland. Apart from PM1 and PM2.5 the concentration of 16 elements, 8 ions and BC for each samples were measured. Based on these chemical species the positive matrix factorization (PMF) receptor modeling was used for the determination of three main sources contribution to the PM1 and PM2.5 concentrations. Daily average concentrations of PM2.5 were 12 µg/m3 in summer and 60 µg/m3 in winter. For PM1 it was 6.9 µg/m3 in summer and 17.3 µg/m3 in winter. These data show a significant difference in percentage contribution of PM1 in PM2.5 in summer (58%) and in winter (29%). For the combustion source, the concentrations calculated from PMF modeling in winter were 4.8 µg/m3 for PM1 and 31 µg/m3 for PM2.5. In summer, the concentrations were smaller than 1 µg/m3 for both fractions. Secondary aerosols' concentration for PM1 was 3.4 µg/m3 in summer and 11 µg/m3 in winter - for PM2.5 these were 7.1 µg/m3 and 17 µg/m3 respectively. The third source - soil, industry and traffic together, had small seasonal variation: for PM1 it was from 1.4 to 1.8 µg/m3 and for PM2.5 from 4.7 to 7.9 µg/m3.

Chemical content and estimated sources of fine fraction of particulate matter collected in Krakow.

The monitored level of pollution remains high in Krakow, Poland. Alerts regarding increased levels of pollution, which advise asthmatics, the elderly, and children to limit their exposure to open air, continue to be issued on numerous days. In this work, seasonal variations in PM2.5 (particulate matter containing particles with aerodynamic diameter no higher than 2.5 µm) concentrations are shown. An increasing trend is reported, which is enhanced during the colder seasons. The mean PM2.5 concentrations in Krakow exceeded the target value of 25 µg/m3 specified for 2015 in the spring, autumn, and winter seasons. For this reason, particulate matter pollution is of special concern. Elemental concentrations as well as the presence of black carbon (BC) and black smoke (BS) in PM2.5 samples were determined. Seasonal variations of Cl, K, Ca, Ti, Mn, Fe, Cu, Zn, Br, Rb, Sr, and Pb concentrations were observed whereas V, Cr, Ni, BC, and BS concentrations did not significantly change with the time of year. Seven factors were identified by the positive matrix factorization (PMF) technique, and one was non-identified. They were attributed to the following sources of pollution: steel industry, traffic (diesel exhaust), traffic (gasoline exhaust, brake wear), road dust, construction dust, combustion (biomass, coal), and non-ferrous metallurgical industry. The last, non-identified source, could be attributed to secondary aerosols. It is worth to mention that combustion shows significant seasonal variations with a high impact in winter. The reported results of the completed studies may significantly aid in solving air quality issues in the city by highlighting major sources of air pollution.