Chemistry Reference
In-Depth Information
PNC personal
PNC ambient
80000
70000
mostly
outdoors
mostly
indoors
mostly
outdoors
60000
50000
40000
30000
20000
10000
0
07:00
08:00
09:00
10:00
11:00
12:00
13:00
14:00
time
Fig. 1 Time series of personal and ambient PNC averaged for all measurements scenarios A and
B(
n
¼
58)
Individual patterns differed substantially from each other. In Fig.
2
two
examples of individual patterns are presented. In Fig.
2a
the personal exposure to
PNC measured indoors was much lower as the ambient PNC. The study participant
spent almost the whole time indoors in an office. The windows were closed during
the whole day. Activities in the office contributed less to PNC as the typically
domestic activities such as cooking or cleaning. The small peak of PNC around
12:30 was recorded during a coffee break in the entrance hall outside of the office.
In Fig.
2b
the influence of two different indoor microenvironments is clearly
visible. Whereas in the office the indoor (personal) PNC levels are lower than the
ambient PNC (similar to Fig.
2a
), the personal PNC were much higher in a
cafeteria. Furthermore, it seems that the air conditioning system which turned on
and off automatically together with some cooking activities caused a very pro-
nounced pattern of PNC going down and up.
3 Model for Indoor Air Quality
Mass balance models are used extensively to describe the concentration in indoor
air as a function of outdoor air and indoor sources. According to Dockery and
Spengler [
6
] the mass-balance of indoor and outdoor generated pollutants can be
expressed as:
Pa
Q
D
C
i
C
i
¼
k
C
a
þ
Þ
(1)
a
þ
V
ð
a
þ
k
D
t
ð
a
þ
k
Þ
