# Bacterial Aerosol in Ambient Air--A Review Study
## 3 Discussion  
It is well recognized that bacteria present in outdoor air are influenced by various factors [55,56]. In an extensive review, [PERSON] et al. [57] discussed factors such as sources, dispersal, deposition, survival, meteorological conditions, location, time, and atmospheric composition, highlighting their impacts on human health and the role of bacteria in regional and global climate feedback mechanisms. Our review focused on air pollutants and meteorological factors, as these parameters are relatively straightforward to measure. Following the methodology of [PERSON] et al. [8], who employed quantitative polymerase chain reaction (qPCR), we aim to test their hypothesis that meteorological factors have a greater influence on shaping airborne bacterial communities than air pollutants. Although culture-independent methods have gained popularity [58, 59, 60], the high cost of PCR has led many researchers to continue using culture-based methods to identify bacteria. Figure 1 illustrates the bacterial measurement points obtained using single- or six-stage impactor culture-based methods, conducted alongside pollutant concentrations and/or meteorological parameters. As shown, no such research has been conducted yet in regions like Africa, where bioaerosols of natural origin play a significant role in public health, agriculture, and the near-surface atmosphere. In such regions, simple and inexpensive culture-based methods can be used for both quantitative and qualitative analyses of bioaerosols [61]. This review examines the correlation coefficients and \(p\) values that indicate the presence or absence of statistically significant relationships between total bacterial concentrations and environmental variables such as particulate matter (PM\({}_{1}\), PM\({}_{2.5}\), and PM\({}_{10}\)) and ozone (O\({}_{3}\)), as presented in Table 1. Additionally, it explores meteorological parameters, including temperature, relative humidity, solar radiation, wind speed, and rainfall, illustrating the complexity of these interactions based on local and temporal conditions (Table 2). A comprehensive table (Table S1) containing all relevant details and results from the selected studies is provided in the Supplementary Materials. Figure 1: Locations where bacteria were measured by culture-based methods simultaneously with meteorological parameters and air pollutants concentrations. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Independent** & \multicolumn{2}{c}{**Correlation**} & \multicolumn{2}{c}{**Total Bacteria**} & **References** \\ \cline{2-5}
**Variable** & \(R\) & \(p\) & **CFU/m3** & \\ \hline PM\({}_{1}\), \(\mu\)g/m3 & & & & \\
68–120 & 0.60 & * & 1963 \(\pm\) 616 & [49] \\ PM\({}_{2.5}\), \(\mu\)g/m3 & & & & \\
12.9 \(\pm\) 8.4 & 0.020 spring & * & 355 (80–1124) & [4] \\
78.8 \(\pm\) 47.8 & \(-\)0.261 winter & * & 65 (4–265) & [4] \\
93.24 \(\pm\) 14.05 & 0.652 & ** & 570 \(\pm\) 313 & [24] \\
40 \(\pm\) 25 & dust days and & \(>\)0.05 & 1–40 & [40] \\
29 \(\pm\) 19 & non-dust days & & 6–68 & [40] \\
16.6–40.4 & & \(>\)0.05 & 35–116 & [43] \\
108.5 \(\pm\) 42.3 & 0.139 autumn & & 523.5 \(\pm\) 301.1 & [47] \\
146.9 \(\pm\) 93.4 & \(-\)0.491 winter & * & 581 \(\pm\) 305.4 & [47] \\
90 (11–230) & 0.6 & * & 4595 \(\pm\) 3410 & [48] \\
95–150 & 0.55 & * & 1963 \(\pm\) 616 & [49] \\
31.3–214.7 & 0.808 & ** & 497.7–1736.5 & [62] \\  & \(-\)0.300 FB & & 129–5035 (FB + CB) & [63] \\
57.04–355.67 & \(-\)0.249 CB & & & \\
8–32 & \(-\)0.0505 & & 36.7–268.04 & [64] \\
13.74–72.57 & 0.77 pre-COVID-19 & & 782 & \\
9.08–62.88 & 0.60 during COVID-19 & & 602 & [65] \\
11.08–61.19 & 0.67 post-COVID-19 & & 529 & \\ PM\({}_{10}\), \(\mu\)g/m3 & & & & \\
27.4 \(\pm\) 21.5 & \(-\)0.067 spring & * & 355 (80–1124) & \\
90.5 \(\pm\) 50.4 & \(-\)0.301 winter & & 65 (4–265) & [4] \\
241 \(\pm\) 165 & 0.573 dust days & * & 1–40 & \\
58 \(\pm\) 32 & non-dust days & \(>\)0.05 & 6–68 & [40] \\
144 (29–315) & 0.6 & * & 4595 \(\pm\) 3410 & [48] \\ \hline \hline \end{tabular}
\end{table}