THE LAWYERS WEEKLY
June 17, 2011 | 13
Are odour units
good science?
Odours are notoriously hard to
manage—and to regulate. For one
thing, there is a huge range of human
sensitivity to odours, so that someone
may complain bitterly about scents
that no one else can detect. For
another, the response to odours is
very subjective, and is strongly
affected by factors outside the control
of the odour source, including the
weather and the mental, physical and
emotional status of the person smell-
ing the odours.
As Justice Ferguson said in Pyke v.
TriGro Enterprises Ltd., [1999] O.J.
DIANNE
SAXE
No. 3217 (aff’d [2001] O. J. No. 3209):
“The...human nose is a very sensi-
tive and a very subjective instru-
ment…The human nose is the ultim-
ate instrument for odour detection…
often below the detection limit of
conventional analytical instrumenta-
tion…The establishment of effective
odour control measures is compli-
cated by the…absence of a direct rela-
tionship between the concentration
and perceived intensity of odours for
humans...a considerable reduction in
concentration of the odour-produ-
cing chemical(s) may be required…to
provide a recognizable change in per-
ceived odour intensity.”
Neighbours often respond more
passionately to “noxious, foul and
penetrating odours” than they do to
other environmental impacts, from
climate change and endangered spe-
