Figures 1c and 1d summarize the odor concentrations and
emission rates of both gestation rooms. For room G2, data
were missing in April due to leaking bags and again in
January because the wall-mounted fans were not operating
due to the low ambient temperature and the research team
was not prepared to access the chimney fans for sampling.
Similar seasonal profiles of odor and CO2 concentrations
were observed in both rooms; however, the odor concentration
in room G2 was much lower. For room G2, CO2 ranged
from 640 to 2,935 ppm, while odor concentration ranged
from 71 to 812 OU/m3. The reason for the much lower odor
concentration throughout the year in room G2 than in G1 was
not clear. The ventilation capacities of the two rooms were
the same (0.085 m3 s−1 pig−1), and the average pig weight per
unit area was much higher in G1 than in G2 (120 and 59 kg/m2, respectively). One possible reason was that some
incoming air to G1 might have been drawn from the two
adjacent gestation rooms by infiltration; this would reduce
the amount of fresh air coming to G1. In contrast, G2 had
three exterior walls, and only one interior wall was shared
with another gestation room.