Table 1: Characteristics of the 78 dwellings where study participants lived between November 2011 and November 2012.

Characteristic	Mean ± SD*
Years since dwelling was built	19.3 ± 8.2
Heating method, no. (%)
Forced air	70 (90)
Radiator	8 (10)
Dwelling occupancy
No. of occupants	6.1 ± 3.0
No. of people per room†	1.1 ± 0.5
Overcrowded,‡ no. (%)	39 (50)
Ventilation
Air changes per hour
With heating off
Living area	0.67 ± 0.28
Bedrooms	0.31 ± 0.28
With heating on
Living area	1.69 ± 0.26
Bedrooms	1.29 ± 0.29
Volume of room, m3
Living area	67.9 ± 9.4
Bedrooms	27.7 ± 4.4

Note: SD = standard deviation.

*Except where noted otherwise.

†Calculated by dividing the number of occupants by the total number of rooms in the dwelling.

‡Occupancy exceeding 1 person per room.²²