Correlation analysis of indoor PM2.5 level with outdoor PM2.5 level, ASD and OD
| Spearman correlation | Partial correlation analysis | ||||
| ρ | p Value | ρ | p Value | Control variables | |
| Outdoor PM2.5 level | 0.58 | <0.001 | 0.37 | <0.001 | ASD, OD |
| ASD | 0.52 | <0.001 | 0.34 | <0.001 | Outdoor PM2.5 level, OD |
| OD | 0.33 | <0.001 | −0.05 | 0.352 | Outdoor PM2.5 level, ASD |
ASD, active smoker density, number of smokers per 100 m3; OD, occupant density, number of occupants per 100 m3.