
Figure 1.
The red circle on the map represents the localization of the measurement point in Gliwice, Upper Silesia, Southern Poland
Table 1.
Meteorological conditions in Gliwice, Upper Silesia Poland, during March 2018–202 3
| Parameters | Year | Temperature | Relative humidity | Atmospheric pressure | Wind speed | Wind Direction a) |
|---|---|---|---|---|---|---|
| Pre-COVID-19 | 2018 avg | 1.71 | 71.81 | 978.94 | 1.23 | SE 23% |
| min | −9.80 | 57.80 | 966.95 | 0.60 | S 23% | |
| max | 11.10 | 92.80 | 992.73 | 3.11 | SW 23% | |
| SD | 5.91 | 8.32 | 5.93 | 0.59 | ||
| 2019 avg | 6.93 | 66.02 | 989.81 | 1.28 | E 19% | |
| min | 0.95 | 53.96 | 975.03 | 0.65 | S 16% | |
| max | 12.03 | 79.52 | 1007.29 | 3.05 | W 23% | |
| SD | 2.61 | 7.30 | 10.06 | 0.57 | ||
| Significant difference between PRE and DURING periods | * | |||||
| During-COVID-19 | 2020 avg | 5.9 | 61.00 | 960.34 | 1.64 | SE 29% |
| min | −0.74 | 35.43 | 971.95 | 0.70 | S 26% | |
| max | 12.13 | 80.35 | 1008.76 | 3.22 | W 16% | |
| SD | 3.71 | 12.67 | 10.27 | 0.64 | ||
| 2021 avg | 4.13 | 71.44 | 996.46 | 1.60 | S 35% | |
| min | −2.24 | 61.47 | 983.71 | 0.53 | SW 23% | |
| max | 13.29 | 88.79 | 1013.38 | 3.34 | W 16% | |
| SD | 4.04 | 7.10 | 7.71 | 0.71 | ||
| Significant difference between DURING and POST periods | * | * | * | |||
| Post-COVID-19 | 2022 avg | 4.42 | 53.65 | 1001.11 | 1.35 | E 23% |
| min | −0.79 | 34.83 | 972.47 | 0.72 | SE 26% | |
| max | 10.87 | 89.29 | 1015.25 | 2.64 | S 19% | |
| SD | 3.59 | 14.34 | 9.15 | 0.45 | ||
| 2023 avg | 7.17 | 66.60 | 989.64 | 0.92 | SE 26% | |
| min | −0.57 | 48.35 | 979.50 | 0.42 | S 23% | |
| max | 14.87 | 87.39 | 998.13 | 2.61 | SW 19% | |
| SD | 4.54 | 10.00 | 5.81 | 0.48 | ||
| Significant difference between PRE and POST periods | * | * | ||||

Figure 2.
Daily bacterial aerosol (BA) concentrations and meteorological parameters during randomly selected days of the non-heating season in Gliwice

Figure 3.
PM2.5 concentrations pre-during, and after- COVID-19 periods

Figure 4.
PM2.5 concentrations pre-during, and after- COVID-19 periods
Table 2.
PM2.5, PM10, NO2 and SO2 levels and the percentages change in concentration
| COVID-19 period | PRE (2018–2019) | DURING (2020–2021) | POST (2022–2023) | ||||
|---|---|---|---|---|---|---|---|
| μg m−3 | % | p | % | p | |||
| PM2.5 avg | 39.28 | 28.35 | 29.11 | −27.8 | 0.01 | +2.7 | 0.81 |
| min | 13.74 | 9.08 | 11.08 | ||||
| max | 72.57 | 62.88 | 61.19 | ||||
| SD | 20.67 | 12.60 | 11.70 | ||||
| PM10 avg | 46.45 | 40.53 | 36.72 | ||||
| min | 16.33 | 14.36 | 17.80 | −12.7 | 0.29 | −8.8 | 0.37 |
| max | 87.65 | 83.13 | 70.37 | ||||
| SD | 24.83 | 17.88 | 15.06 | ||||
| NO2 avg | 24.05 | 21.76 | 27.82 | −9.5 | 0.28 | +27.8 | 0.08 |
| min | 10.61 | 10.55 | 8.87 | ||||
| max | 47.51 | 42.04 | 51.97 | ||||
| SD | 8.50 | 8.18 | 9.17 | ||||
| SO2 avg | 14.57 | 9.62 | 10.82 | −34.0 | 0.001 | +12.5 | 0.26 |
| min | 5.12 | 5.19 | 4.59 | ||||
| max | 28.19 | 25.49 | 17.90 | ||||
| SD | 6.70 | 4.78 | 3.52 | ||||
Table 3.
Spearman correlation coefficients between bacterial aerosol concentrations and environmental parameters
| BA | PM10 | PM2.5 | SO2 | NO2 | T | RH | P | Ws | Wd | |
|---|---|---|---|---|---|---|---|---|---|---|
| Pre-COVID-19 | ||||||||||
| BA | 1 | 0.89 | 0.77 | 0.63 | 0.59 | −0.27 | 0.05 | −0.13 | −0.06 | 0.11 |
| PM10 | 1 | 0.99 | 0.86 | 0.89 | −0.03 | 0.31 | 0.72 | −0.49 | 0.07 | |
| PM2.5 | 1 | 0.88 | 0.87 | −0.08 | 0.44 | 0.66 | −0.53 | 0.06 | ||
| SO2 | 1 | 0.89 | 0.04 | 0.13 | 0.71 | −0.53 | −0.04 | |||
| NO2 | 1 | −0.15 | 0.25 | 0.82 | −0.44 | 0.19 | ||||
| T | 1 | −0.45 | −0.23 | −0.17 | −0.45 | |||||
| RH | 1 | 0.33 | −0.13 | 0.23 | ||||||
| P | 1 | −0.23 | 0.38 | |||||||
| Ws | 1 | 0.61 | ||||||||
| Wd | 1 | |||||||||
| During-COVID-19 | ||||||||||
| BA | 1 | 0.80 | 0.60 | 0.58 | 0.41 | 0.28 | −0.10 | −0.27 | 0.05 | −0.02 |
| PM10 | 1 | 0.91 | 0.71 | 0.34 | 0.16 | −0.36 | 0.44 | −0.54 | 0.06 | |
| PM2.5 | 1 | 0.47 | 0.11 | -0.14 | −0.18 | 0.27 | −0.40 | 0.06 | ||
| SO2 | 1 | 0.57 | 0.31 | −0.61 | 0.28 | −0.37 | 0.11 | |||
| NO2 | 1 | 0.62 | −0.27 | 0.45 | −0.23 | 0.15 | ||||
| T | 1 | −0.16 | 0.43 | −0.12 | 0.18 | |||||
| RH | 1 | −0.28 | 0.19 | 0.21 | ||||||
| P | 1 | −0.29 | −0.03 | |||||||
| Ws | 1 | 0.04 | ||||||||
| Wd | 1 | |||||||||
| Post-COVID-19 | ||||||||||
| BA | 1 | 0.81 | 0.67 | 0.34 | 0.58 | 0.41 | −0.20 | 0.13 | −0.07 | 0.09 |
| PM10 | 1 | 0.95 | 0.56 | 0.85 | 0.53 | −0.35 | 0.29 | 0.41 | −0.07 | |
| PM2.5 | 1 | 0.46 | 0.81 | 0.41 | −0.37 | 0.37 | −0.44 | −0.08 | ||
| SO2 | 1 | 0.61 | 0.21 | −0.75 | 0.70 | −0.06 | −0.63 | |||
| NO2 | 1 | 0.05 | −0.63 | 0.63 | −0.50 | −0.07 | ||||
| T | 1 | −0.44 | 0.09 | −0.52 | −0.11 | |||||
| RH | 1 | −0.82 | 0.18 | 0.43 | ||||||
| P | 1 | 0.02 | 0.32 | |||||||
| Ws | 1 | 0.01 | ||||||||
| Wd | 1 | |||||||||
[i] Italic entries indicate that the correlation is significant at the 0.05 level; BA (CFU m−3), concentrations of air pollutants (μg m−3), Temperature, T (°C); Relative humidity, RH (%); Atmospheric pressure, P (hPa), Wind speed, Ws (km h−1); Wind direction, Wd (°).

Figure 5.
Shares of emission sources in individual air pollutants in the Silesian province compiled by GIOS, data source: KOBIZE / IOS-PIB

Figure 6.
Wind rose diagram for March 2018–2023

Figure 7.
PM2.5 concentrations pre-during, and after- COVID-19 periods

Figure 8.
PM2.5 concentrations pre-, during, and after- COVID-19 periods

Figure 9.
Bacteria aerosol concentrations pre-during, and after-COVID-19 periods
