# Particle Number of Aerosol in Specific Conditions of Biotechnology Laboratory Cleanroom
## 4 Discussion  
The results of the measurements showed that the laboratory area could be classified as falling into ISO cleanliness class 8. This result was similar to those of the measurements \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Fraction** & **February/May** & **February/July** & **May/July** \\ \cline{2-3}
**(\(\mu\)m)** & & \(p\) Value** & \\ \hline
0.3–0.5 & 0.071 & 0.071 & 0.000 1 \\
0.5–1.0 & 0.000 1 & 0.059 & 0.102 \\
1.0–2.0 & 0.071 & 0.000 1 & 0.071 \\
2.0–5.0 & 0.071 & 0.000 1 & 0.071 \\
5.0–10.0 & 0.867 & 0.000 1 & 0.013 1 \\ \(>\)10.0 & 0.169 & 0.044 1 & 0.000 1 \\ \hline \hline \end{tabular} \({}^{\dagger}\) Statistically significant difference at the \(\alpha\) level = 0.05.  
\end{table} 
Table 4: Calculated \(p\) values for the office. Figure 4: (**A**) Cumulative particle number for fraction \(>\) 0.5 \(\mu\)m in the office. (**B**) Cumulative particle number for fraction \(>\) 1.0 \(\mu\)m in the office. (**C**) Cumulative particle number for fraction \(>\) 5.0 \(\mu\)m in the office. that were performed in a different pharmaceutical laboratory ([PERSON] et al., 2012) [15]. In this instance, pharmaceutical laboratories were classified as either ISO cleanliness class 7 or 8. Unfortunately, this study did not contain information about HVAC, mode of work, and materials used in more detail. A study by ([PERSON] et al., 2021) [14] was carried out in a biopharmaceutical production line. This study contained the description of HVAC, layout, and other equipment in more detail. Measured rooms were equipped with a buffer room and airlock to prevent the invasion of pollutants. Due to the HVAC used, the measured particle number values were very low. These values ranged from 281 to 3194 pc/m\({}^{3}\) (for particles larger than 0.5 \(\upmu\)m) depending on the location of the measurement and the type of room. HEPA H14 was used for air cleaning in these rooms, i.e., a filter was used with the ability to capture up to 99.995% of particles with a diameter greater than 0.3 \(\upmu\)m. For comparison, in our study, the HEPA E12 filter was used (99.5% particle capture with a diameter greater than 0.3 \(\upmu\)m). In the study by ([PERSON] et al., 2021) [20], HEPA H13 was used in the operating rooms. Here, values ranged from 7944 to 21,631 pc/m\({}^{3}\) for PM 0.5. The authors ([PERSON] et al., 2015) [13] state that the HEPA filter H14 was probably used in the operating room. Here, the values ranged from nearly 10,000 to approximately 70,000 pc/m\({}^{3}\) depending on the location of the measurement point. However, it is not possible to estimate from the results of studies as to why such large differences between the results of different research, e.g., the [PERSON] et al. (2021) study and the [PERSON] et al. (2015) study. Comparing the results of our study with those of other studies, it is clear that the use of the type of filter can have a decisive influence on the number of particles in the room. There are no national standards for laboratory room cleanliness, the factor tested in our study. [PERSON] et al. (2012) state that the laboratory area must meet at least ISO 14644 class 7. This is likely an internal standard of the laboratory. From the results of our study, the biotechnology laboratory space was classified as ISO class 8. Particles with a size of 5.0 \(\upmu\)m and above play an important role in this from the point of view of the possibility of sample contamination by microorganisms. The authors ([PERSON] et al., 2021) [20] state that the measurement of PM5 and PM10 can be used to monitor microbiological contamination. Unfortunately, the cumulative particle counts for the fraction \(>\)5.0 \(\upmu\)m in the laboratory exceeded the limit value for ISO class 7. There are several ways to further reduce the particle concentration. First of all, these are structural and technical adaptations that can be made to laboratory rooms. The laboratory should be equipped with a buffer room and an airlock (see [PERSON] et al., 2021) [14]. Further, [PERSON] et al.