Environmental Engineering Reference
In-Depth Information
Table 4.5
Effect of Temperature and Relative Humidity on Formaldehyde
Levels in a Mobile Home Under Controlled Environmental Conditions
Temperature
(°C)
Relative humidity
(%)
Concentration
(ppmv)
% maximum value
30
70
0.36
100
25
70
0.29
81
30
50
0.28
78
30
30
0.23
64
25
50
0.17
47
25
30
0.14
39
20
70
0.12
33
20
50
0.09
25
20
30
0.07
19
tions of particle board, MDF, Luan plywood, and hardwood). As a conse-
quence, they had relatively high surface/volume ratios (expressed as m
/m
)
2
3
of formaldehyde-emitting wood products.
Environmental factors such as
temperature and humidity have significant effects on HCHO levels in build-
ings where UF-bonded wood products are major HCHO sources. The effects
of temperature on indoor HCHO concentrations is exponential, whereas the
effect of relative humidity is linear. Combined effects of various temperature
and humidity regimes on HCHO levels in a mobile home can be seen in
(30°C, 70% RH) resulted in indoor concentrations that were 5 times greater
than the lowest combination (20°C, 30% RH).
Experimentally derived relationships between HCHO levels and tem-
perature and HCHO levels and relative humidity have been used to develop
equations to “correct” (or more appropriately, standardize) HCHO levels
determined under different environmental conditions to temperature and
humidity conditions such as 25°C and 50% RH. The Berge equation is widely
used to standardize HCHO concentrations. It has the following form:
b.
Temperature and relative humidity.
C
C
X
=
---------------------------------------------------------------
(4.1)
e
-R(1/T-1/T
O
)
[
1
+
A(H-H
O
)
]
where C
= standardized concentration (ppmv)
X
C
= measured concentration (ppmv)
e
= natural log base 2.7818
R
= coefficient of temperature (9799)
T
= temperature at test (°K)
T
= standardized temperature (°K)
O
A
= coefficient of humidity (0.0175)
H
= relative humidity at test (%)
H
= standardized relative humidity (%)
O
