## 3 Results and Discussion
### Offactometric Measurements  
In Table 4 the average odor concentrations (ouE m\({}^{-3}\)) \(\pm\) standard deviation, for each session, measured by olfactometric analysis for DF, WAS and CR, are presented. In order to satisfy the requirements of EN 13725, the panel was tested using \(n\)-butanol for accuracy and repeatability before each olfactometric session. Accuracy (A\({}_{\text{od}}\)) ranged from 0.098 to 0.160 and repeatability (r) ranged from 0.268 to 0.322, with a 95% confidence interval, confirming the panel selection criteria. As expected, odor concentration increases during time in correspondence of an increasing animal live weight. Pig weight at the beginning of the cycle was 28 kg and the average daily gain was 0.93 kg. November sessions odor concentration measured by dynamic olfactometry was higher than September ones. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Session** & **Wet Acid Scrubber** & **Dry Filter** & **Control** \\ \hline
1 (7–10 September 2020) & \(1102\pm 175\) & 2285 \(\pm\) 446 & 3260 \(\pm\)1168 \\
2 (15–17 September 2020) & \(2617\pm 562\) & 11,220 \(\pm\) 1490 & 10,131 \(\pm\) 1572 \\
3 (17–22 September 2020) & 8287 \(\pm\) 2064 & 10,001 \(\pm\) 567 & 10,131 \(\pm\) 1572 \\
4 (29 October–2 November 2020) & 34,123 \(\pm\) 4317 & 38,339 \(\pm\) 10,078 & 34,112 \(\pm\) 3860 \\
5 (24–25 November 2020) & 104,329 \(\pm\) 9112 & 163,478 \(\pm\) 36,340 & 57,911 \(\pm\) 23,101 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Average \(\pm\) standard deviation odor concentrations (ouE m\({}^{-3}\)) for each abatement system and for the control room. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Sampling Date** & **T**, \({}^{\circ}\)**C** & **RH, \%** & **Wind Speed, m/s** & **Wind Direction** \\ \hline
7 September & 22 & 84 & 1.78 & SSW \\
9 September & 23 & 80 & 1.43 & E \\
15 September & 24 & 72 & 1.61 & E \\
17 September & 24 & 70 & 1.26 & S \\
21 September & 19 & 96 & 1.55 & SSE \\
29 October & 11 & 95 & 1.12 & WSW \\
2 November & 11 & 100 & 0.70 & S \\
24 November & 4 & 89 & 1.21 & WSW \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Mean meteorological data. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Sampling Date** & **T**, \({}^{\circ}\)**C** & **RH, \%** & **Windows** \\ \hline
7 September & 20.1 & 81.1 & Open 70\% \\
9 September & 20.6 & 77.2 & Open 90\% \\
15 September & 21.2 & 73.0 & Open 80\% \\
17 September & 21.1 & 72.8 & Open 60\% \\
21 September & 18.7 & 84.6 & Open 80\% \\
29 October & 17.2 & 84.1 & Open 10\% \\
2 November & 19.3 & 81.0 & Open 5\% \\
24 November & 10.7 & 83.2 & Open 50\% \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Average environmental conditions inside the barns. Generally, WAS registered lowest values compared to DF and CR, except for the last session. The 24 th of November, slurry pits in WAS and DF rooms were emptied during collection of air samples, substantially increasing the ouE m\({}^{-3}\) measured. Nevertheless, WAS always presents lower odor concentration values than DF room and, excluding session 5, also lower than CR. Results show a detected odor concentration for all analyzed samples between 1102-163,478 ouE m\({}^{-3}\). Environmental conditions inside and outside the rooms could have influenced the final result. Although samples were collected always in the morning around 10 a.m., away from meals, to have repeatable test conditions, external variables, such as windows opening and pits emptying, certainly affected the results. In laboratory, uncertainties associated with odor quantification, were reduced using the same olfactometer and the same panel. Assessors were selected only using \(n\)-butanol as a standard reference odorant; although, as underlined by [PERSON] et al. [34], this gas does not reflect the characteristics and intensities of odors associated with pig farming. Consequently, knowing the major odorous compounds associated to swine facilities, is crucial for developing odor control strategies.