. Location of air-flow corridors and Regional Environmental Protection Inspectorate air monitoring stations in Kraków. Table S1 . Description of the air monitoring stations operated by the Regional Environmental Protection Inspectorate (REPI) in Kraków. Table S2 . Ranges of the 1h concentrations in the Polish air quality index (AQI) for selected pollutants. Table S3 . The Polish AQI index and the corresponding health recommendations for residents. Table S4 . Description of the enrichment indices used in the study. Table S5 . Exposure parameters used for the risk assessment calculations under resident scenario in the study. Table S6 . Toxicological parameters used for the risk assessment calculations under resident scenario in the study. Table S7 . Changes in annual air pollutant contents in Kraków in 2005-2020, with permissible levels. Table S13 . Changes in monthly air-pollutant contents in the first half of 2020 in Kraków, average values from all the monitoring stations. Table S14 . Estimated daily intake values for the resident of Kraków, in reference to exposure pathways. Figure S1 . A demonstrative wind rose in Kraków Poland: share of wind directions in % (a), and wind speed distribution in m/s (b), divided into cool and warm half-years [1] . Figure S2 . Location of air-flow corridors and Regional Environmental Protection Inspectorate air monitoring stations in Kraków (modified after [2] ). Table S1 . Description of the air monitoring stations operated by the Regional Environmental Protection Inspectorate (REPI) in Kraków [3] . Industrial district Table S2 . Ranges of the 1h concentrations in the Polish air quality index (AQI) for selected pollutants [3] . [3] .
Very good Good air quality. Air pollution is not a threat. Ideal conditions for outdoor activities.
Good Good air quality. Air pollution poses a minimum threat to those at risk. Very good conditions for outdoor activities.
Moderate Acceptable air quality. Air pollution can pose a risk to people at risk. Good conditions for outdoor activities.
Average Average air quality. Air pollution is a threat to those at risk who may experience health effects. Other people should limit spending time outdoors, especially if they experience such symptoms as coughing or sore throat.
Bad Bad air quality. People at risk should avoid going outside. Other residents should limit staying outdoors. Outdoor activities are not recommended.
Dangerously bad air quality. People at risk should definitely avoid going outside. Others should keep exits to a minimum. All outdoor activities are discouraged. Table S4 . Description of the enrichment indices used in the study [4] . [16, 17] 0.5< mHQ <1.0 very low severity of contamination 1.0< mHQ <1.5 low severity of contamination 1.5< mHQ <2.0 moderate severity of contamination 2.0< mHQ <2. 5 considerable severity of contamination 2.5< mHQ <3.0 high severity of contamination 3.0< mHQ <3. 5 very high severity of contamination mHQ >3.5 extreme severity of contamination * site specific; assumption: two weeks of holidays each year Table S6 . Toxicological parameters used for the risk assessment calculations under resident scenario in the study.
Ambient air
3.00 × 10 -2 7.80 × 10 -9 4.00 × 10 -3 5.50 × 10 -2 --PM2. 5 5.00 × 10 - (20**) 6*** 5*** 20*** 500 -------data not available; * until the end of May 2020; ** since 2020; *** [30] ; bold: the concentrations exceeding the recommended levels. Colors refer to the following air quality index (AQI) codes: dark green -very good; green -good; yellow -moderate; orange -average; red -bad; maroon -very bad. 1240 1015 736 2316 1854 1526 1481 1259 1699 1675 1703 509 447 947 354 600 119 137 241 324 970 588 1801 1493 1398 1032 874 533 500 633 1008 06:00 1356 1116 809 2215 1793 1518 1811 1528 1790 1732 1718 567 602 1002 412 545 128 111 294 604 1093 645 1790 1450 1297 1090 1043 779 649 1001 974 07:00 1488 1277 907 2120 1891 1512 1754 1864 1911 1774 1745 646 858 1287 691 584 156 126 367 663 744 794 1750 1285 1268 1275 1181 897 Colors refer to the following air quality index (AQI) codes: dark green -very good; green -good; yellow -moderate; orange -average; red -bad; maroon -very bad. Table S13 . Changes in monthly air-pollutant contents in the first half of 2020 in Kraków, average values from all the monitoring stations [3] . Be 9.14 × 10 -9 9.14 × 10 -9 3.27 × 10 -9 7.83 × 10 -10 Cd Cd 2.32 × 10 -10 5.41 × 10 -10 7.94 × 10 -11 4.63 × 10 -11 1.49 × 10 -6 1.16 × 10 -5 5.11 × 10 -7 9.95 × 10 -7 6.65 × 10 -9 3.49 × 10 -8 2.28 × 10 -9 2.99 × 10 -9
Co 4.73 × 10 -10 1.10 × 10 -9 1.62 × 10 -10 9.47 × 10 -11 3.00 × 10 -6 2.25 × 10 -5 1.03 × 10 -6 1.93 × 10 -6 1.36 × 10 -5 7.13 × 10 -5 4.66 × 10 -6 6.11 × 10 -6
Cr(III) 1.81 × 10 -8 4.23 × 10 -8 6.22 × 10 -9 3.63 × 10 -9 1.14 × 10 -4 8. Zn 1.17 × 10 -6 2.74 × 10 -6 4.02 × 10 -7 2.34 × 10 -7 6.41 × 10 -3 3.49 × 10 -2 2.20 × 10 -3 2.99 × 10 -3 3.37 × 10 -2 1.77 × 10 -1 1.15 × 10 -2 1.51 × 10 -2 Zr 9.17 × 10 -10 2.14 × 10 -9 3.14 × 10 -10 1.83 × 10 -10 4.96 × 10 -6 2.64 × 10 -5 1.70 × 10 -6 2.27 × 10 -6 2.63 × 10 -5 1.38 × 10 -4 9.02 × 10 -6 1.18 × 10 -5
-not applicable to the available data