defined another index showing the effects of contaminant
inhalation, IECI, using the product of the concentration of
contaminants in the air C(x) and the portion of the air to
be inhaled SVE5, which is IECI = C(x)SVE5. The index
IECI is very convenient in evaluating the health effects from
inhalation of contaminated air. The more regions there are with low IECI values, the more favorable the environment
is for the occupant.
(i) Standing. When the occupant is standing, the contaminants
emitted from the floor do not form areas with
large concentration gradients. Thus the distribution of IECI becomes somewhat similar to that of the inhalation region
as is shown in Fig. 15(1). The standing occupant inhales the
contaminated air drawn up from the lower part of the body.
The air behind the occupant has little effect.
(ii) Sleeping. When sleeping, the region of SVE5 with
a higher value coincides almost exactly with the region
of higher concentration of contaminants emitted from the
floor.Accordingly, the distribution of IECI is higher in the area
adjacent to the head of the occupant, and is near to 0 through-
out the rest of the area as is shown in Fig. 15(2).
3.2.5. Residual lifetime of air to be inhaled
Residual lifetime of the air to be inhaled at each point is
calculated by the average time taken by a tracer to move rนom the point to the mouth when the tracer is emitted in a
pulse at this point.
(i) Standing. When an occupant is standing, inhalation
residual lifetime is shorter in the area from the mouth to
the lower area as is shown in Fig. 16(1). It is clear that the
fresh air from the supply opening enters the region of inhalation, drawn upward by the thermal resulting from metabolic heating. The air in the region extending from the head to
the exhaust opening hardly reaches the region of inhalation
at all, but moves away towards the exhaust opening. Interestingly,
the distribution of residual lifetime for air to be
inhaled corresponds inversely to that of IECI. In the region
of higher IECI, the residual lifetime for air to be inhaled is
shorter (Fig. 15(1)).
(ii) Sleeping. The residual lifetime for air to be inhaled
is relatively low when sleeping on the floor compared to
that when standing, as is shown in Fig. 16(2). The air near
the chest is transported to the upper part of the room by the
rising air stream due to metabolic heating.