Air filters from different apartments in the same Toronto
Community Housing building. Upper left is “almost certainly” from
a smoker’s unit, says Prof. Jeff Siegel. Lower right never left its case.
The one next to it is from a unit where the resident is rarely home. Photo by Eric Li.

Add a Comment

required, use real name
required, Not for Publication
optional, eg: BSc 2008

Previous story in this issue: «