Lower TIP was found in apartments with high PM2.5 concentrations
(p ¼ 0.04) and greater room volume (p ¼ 0.02). This and/or
higher PM2.5 concentrations mass might lead to varying microbial
composition. Both room volume and PM2.5 changed direction from
being positively associated with TIP in univariate analysis to being
negatively associated in multivariate analysis (Table 5). However,
the univariate analysis was not significant for PM2.5 concentrations
or room volume.
Other parameters, such as wooden floor (as compared to carpet)
and year of construction (older homes as compared to newer) did
not show significant associations with TIP in multivariate analyses.