Low levels of bacteria were measured in dwellings located on
higher floor levels in univariate analysis (p < 0.01), but this association
lost significance in the multivariate analysis (Table 3).
Bacteria levels were not associated with concentrations of PM2.5
mass. Similar to fungi, bacteria levels were in another study found
to be correlated with larger particle size-ranges (3e5 mm in
diameter in collected mass) [43].
Table 2
Concentrations of fungi measured in tested dwellings.
Univariate association Multivariate association
% difference (95% CI)a P-value % difference (95% CI)b P-value
Temperature (C) 4.0 (9.5; 17.5) 0.58 35.5 (5.4; 46.5) 0.18
Indoor air RH (%) 4.0 (0.3; 8.3) 0.08 9.4 (1.8; 17.1) 0.03
Area p. person (m2/pers.) 3.7 (0.1; 7.2) 0.05 0.9 (7.4; 3.1) 0.10
Room volume (m3) 0.8 (0.0; 1.6) 0.05 1.3 (0.3; 2.9) 0.03
Floor level
>1st floor (n ¼ 18) 42.5 (15.9; 101) 0.24 124.1 (57.9; 190) 0.02
grounde1st floor (n ¼ 9) e e e e
Floor material
Carpet (n ¼ 4) 51.7 (26.1; 130) 0.30 43.3 (33.7; 120) 0.28
Wood or linol. (n ¼ 23) e e e e
Pets
No (n ¼ 21) 87.2 (22.3; 152) 0.06 78.6 (10.1; 161) 0.11
Yes (n ¼ 6) e e e e
Year of construction
17th century e 1900 (n ¼ 9) 44.1 (123; 34.5) 0.15 43.1 (170; 34.3) 0.12
1901e1960 (n ¼ 11) 4.5 (71.4; 80.4) 0.91 73.3 (49.0; 195.6) 0.32
1961epresent (n ¼ 7)
AER (h1) 78.8 (187; 29.8) 0.1 69.9 (145; 15.4) 0.16
a Estimated change in average fungi concentrations (in CFU m2 day1). For example, a change of the variable floor level 42.5 is interpreted as 42.5% increase of
CFU m2 day1 of fungi in dwellings located above the first floor compared with group of dwellings on the ground and first floor.
b The model in the multivariate association explained 48% of the variance (R2 ¼ 0.48).