## 4 Conclusions  
The concentrations of SNA precursor gases and PM\({}_{2.5}\) at a modern manure comprising facility in Paju, South Korea were continuously measured over a period of 35 days in June and July 2021. Average internal NH\({}_{3}\) concentrations were 57.1 \(\pm\) 1.3 mg m\({}^{-3}\), compared with external NH\({}_{3}\) concentrations of 3.64 \(\pm\) 0.06 mg m\({}^{-3}\) at 3 m height and 2.43 \(\pm\) 0.16 mg m\({}^{-3}\) at ground level. Internal concentrations of NH\({}_{3}\) were found to differ significantly between daytime (higher) and nighttime (lower), and weekend nights had concentrations that were significantly lower than weekday nights. These concentration differences are likely to have been caused by manure agitation activity, which occurred during weekday daytimes, and temperature differences between day and night. Sulfur dioxide (SO\({}_{2}\)) concentrations followed a similar pattern to NH\({}_{3}\), and SO\({}_{2}\) was found to be the second most abundant precursor gas, with average concentrations of 307.2 \(\pm\) 17.4 \(\mu\)g m\({}^{-3}\). Weekend nighttime concentrations of SO\({}_{2}\) were found to be significantly lower than at all other times. The predominant component of NOx gases was determined to be NO, with average concentrations of 33.4 \(\pm\) 3.2 \(\mu\)g m\({}^{-3}\), compared with NOx concentrations of 7.3 \(\pm\) 0.8 \(\mu\)g m\({}^{-3}\). Although there were no significant differences between NOx concentrations at different times, the NOx concentration profile was markedly different to both NH\({}_{3}\) and SO\({}_{2}\), suggesting that the processes governing emissions were different. Average PM\({}_{2.5}\) concentrations inside the facility (36.9 \(\pm\) 2.6 \(\mu\)g m\({}^{-3}\)) were about 50% higher than external concentrations (23.7 \(\pm\) 2 \(\mu\)g m\({}^{-3}\)), and a moderate correlation (r = 0.341, \(p\) < 0.001) between the two suggested that ambient PM\({}_{2.5}\) contributed part of the internally measured concentrations. The NH\({}_{3}\) emission rate from the facility's manure agitation hall was calculated to be 7.28 \(\pm\) 0.41 NH\({}_{3}\)-N mg min\({}^{-1}\) m\({}^{-3}\), corresponding to scaled emissions rates \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Emission Rate** & \multicolumn{3}{c}{**Scaled Emission Rates**} \\  & **mg min\({}^{-1}\) m\({}^{-3}\)** & **g h\({}^{-1}\) m\({}^{-2}\) Manure** & **g h\({}^{-1}\) m\({}^{-3}\) Manure** & **g kg\({}^{-1}\) Manure \({}^{*}\)** \\ \hline Mean & 7.28 & 2.77 & 1.85 & 1.52 \\ Std. Error & 0.41 & 0.16 & 0.1 & 0.09 \\ \hline \hline \end{tabular} \({}^{*}\) over the entire 18-day composting period.  
\end{table} 
Table 4: NH\({}_{3}\) emission rates inside the Paju Manure Composting Facility under non-ventilated conditions. of 1.85 \(\pm\) 0.1 NH\({}_{3}\)-N g h\({}^{-1}\) m\({}^{-3}\) for manure compost and 1.52 \(\pm\) 0.09 NH\({}_{3}\)-N g kg\({}^{-1}\) for manure compost over the full 18-day composite period. Based on these figures, total daily NH\({}_{3}\) flux from the manure agitation hall was approximately 24.47 \(\pm\) 1.39 NH\({}_{3}\)-N kg d\({}^{-1}\). The data from this study suggest that despite the large fluxes of NH\({}_{3}\) and other precursor gases emitted inside the manure composite facility, the sealed building design with a negative-pressure high-volume ventilation/scrubber system is effective at minimizing NH\({}_{3}\) and PM\({}_{2.5}\) emissions to the atmosphere. Conceptualization, S.-R.L. ; methodology, S.-R.L. ; software, S.-R.L. ; validation, S.-R.L. ; formal analysis, S.-R.L. ; investigation, S.-R.L. ; resources, S.-R.L. ; data curation, S.-R.L. ; writing--original draft preparation, S.-R.L. ; writing--review and editing, S.-R.L. and G.K.; visualization, S.-R.L. ; supervision, S.-R.L. ; project administration, S.-R.L. ; funding acquisition, S.-R.L. All authors have read and agreed to the published version of the manuscript.