Available via license: CC BY 4.0
Content may be subject to copyright.
*
Corresponding author: w.zeiler@tue.nl
The CO2 conditions within the baby cots of day care centres
Gert-Jan Braun
1
and Wim Zeiler
1,*
1
TU Eindhoven, Department of the Built Environment, 5600 MB Eindhoven, Netherlands
Abstract. The indoor quality of an occupied space is very important for the well-being of its occupants,
especially in the case of young children. Although nowadays little children spend a lot of their time in day
care centres, relatively little is known about the effects of different indoor environmental factors present in
these day care centres. Therefore this research investigated the indoor air quality of the sleeping
accommodation of two Dutch day care centre as well as the conditions with the baby cots. Besides an
extensive literature research actual measurements were performed in two day care cent to find out the indoor
air conditions within baby cots. The results of the detailed studies were compared with the results of earlier
Dutch studies in day care centres. Although, our latest findings were not as bad as results from our earlier
case studies, still more attention is needed to get a better understanding of the current situation in which babies
sleep.
1 Introduction
Young children, and their immune system, are
continuously under development. Adverse conditions
could influence this development [1], or might even
increase the risk of sudden infant death [2,3]. Children are
more vulnerable to airborne pollution due to the fact that
their airways are narrower than adults, they have
markedly increased needs for oxygen relative to their
seize, they breathe more rapidly and inhale more
pollutants per pound of body weight [4]. Babies and little
children spend a lot of their time in day-care centers while
parents are at work. The infants normally stay at a child
day-care centre until their fourth birthday. Strangely
enough little is known about the indoor environmental
conditions in these day-care centers [5, 6, 7, 8, 9, 10, 11,
12]. This while a healthy environment is very important
for the development of infants and especially their longs
as such they are the most vulnerable group of our
population. Table 1 provides an overview of some studies,
in most cases between 20 up to 75% of all measured
daycare centers had CO
2
concentrations well above the
recommended level by the Dutch government of 1000
ppm in class rooms and 800 ppm in sleeping rooms.
In most studies the overall CO
2
level is measured in the
class rooms and in some also in the bedroom. Therefor it
was decided to examine especially the ventilation of the
daycare bedrooms in detail. The objective of this research
is to determine CO
2
concentration in the breathing zone of
a sleeping infant of baby cots used in child day care
centres and see if they meet the demands in the Dutch
building code of 2012. Field studies have been done
among the different types of baby cots in different daycare
centers to measure the CO
2
concentrations inside these
baby cots [13,14] of which an overview was made [17]
Table 1. Overview of CO
2
concentrations in daycare centers
from different studies
Year Location Number Average CO
2
[ppm]
Reference
2005 Netherlands 51-62 920 (bedrooms)
1297 (class
room)
[5]
2009 Netherlands 60 1452 [7]
2011 Latvian 4 731 [8]
2011 Paris 28 933 [9]
2012 Montreal 21 1333 [17]
2014 Portugal 52 1563 [10]
2016 Italy 1 1100 [11]
2016 Europe 4 1128 [12]
In this paper the results of further investigations in two
more modern daycare centers are presented.
The results
of the measured CO
2
concentrations inside baby cots of
day-care centers made it clear why it is important to focus
also on the ventilation effectiveness inside baby cots and
not only on the ventilation rates in general. These effects
can lead to CO
2
concentrations which can be on average
around 25% (with in some situations even up to nearly
60% higher) than the average concentrations in the
sleeping rooms of the day-care centers from the extensive
research by Versteeg in 2009 [7].
2 Methods
As stated in section one, the goal of this research is to
determine what the CO
2
concentration are near a sleeping
infant and to see if they meet the current demand of the
Dutch building code 2012. To determine this
measurements were performed in different type of baby
cots in two day care centres The purpose of these
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© The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative
Commons Attribution License 4.0
(http://creativecommons.org/licenses/by/4.0/).
measurements was to obtain enough CO
2
data to compare
the conditions within a specific baby cot and to determine
if the differences between these baby cots are significant
and accountable for possibly higher CO
2
concentrations.
In our earlier research [13,14] , different types of baby
cots were monitored inside the day care centre, see Figure
1. The first type, a crib is used for children in the age of 2
-4 and which tend not to get out of bed while sleeping.
The second type, the bedstead, is used by both new bourns
as children in the age of 2 -4. The last type was the bunk
bed used, top and bottom, with children in the age of 10
weeks up to 2 years.
Figure 1. Different types of baby cots
2.1 Measurement setup
In the research of de Waard [13], the breathing zone was
determined to be ± 0.3m. This is therefore the distance
that was aimed to apply in the ‘practical conditions’. The
general setup can be seen in Figure 2.
Figure 2. General measurement setup
1. Two CO
2
sensors
2. Cable bundler
3. Two pressure sensors
4. Central box
5. Mains supply
The equipment used during the measurement is
displayed in Table 2.
Table 2. Measurement equipment
Measurement Device Interval Inaccuracy
CO
2
SBA-% CO
2
Analyser
1 sec ± 20 ppm
Data logging Squirrel 2020
series
1 sec ±0,075%
To ensure to safety of the infant inside (and outside) the
crib, none of the equipment was placed inside the crib.
Also all the wires where made unreachable from inside
the crib.
2.2. Measurements
The measurement results are gathered from the 18th of
June until the 21st of June. All the measurement took
place in the Netherlands, in ‘den Haag’. In total two
location were measured over a period of two days, [1]
respectively [2] in table 5, each at a different room, these
locations can be seen in Table 3. Both locations where
recently renovated and where mechanically ventilated,
meeting the ventilation demands of the Dutch building
code 2012.
Table 3. Measured locations
All date generated during the measurements were stored
on a logger. Afterwards the logger can be read out and
the data can be used for analysis. During the
measurement a logbook was kept to store all the actions
that might have an effect on the registered data. For an
example of this logbook see Table 4.
Table 4. Example logbook location A room 2
Time Action
9.17 Measurement started
9.58 –
10.07
Test baby is placed in the crib (and 4 others)
10.55-
10.58
Baby is taken out of the crib (and 4 others)
11.00 Measurement setup is checked
12.00 One baby is placed in other crib
13.15 Another baby is placed in the crib (stacked crib)
15.01 2 babies are taken out of their crib
15.05 Test baby and four other baby are placed in their bed
15.07 Measurement setup is checked
16.14 Test baby and all the other babies are taken out of
the crib
16.21 Fine particle measurement installed
16.32 Measurement setup turned off
Date Location Room
18-06-2018 A 1
19-06-2018 A 2
20-06-2018 B 3
21-06-2018 B 4
Crib
Bedstead
Bottom bunk bed
Top bunk bed
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3. Results
Location A, room 1
Figure
3
.
Measurement setup and results location A, room 1
Location A, room 2
Figure
4
.
Measurement setup and results location A, room 2
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Location B, room 3
Figure
5
.
Measurement setup and results location B, room 3
Location B, room 4
Figure 6
.
Measurement setup and results location B, room 4
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*
Corresponding author: w.zeiler@tue.nl
3.2. CO
2
levels
The CO
2
concentration during nap-time (the infant is
inside the crib) is summed up in Table 5. Each percentage
resembles the amount of time during nap-time that the
CO
2
concentrations are within the listed classes. The
listed classes are based on the test values for ventilation
in schools and child daycares [15]. The classes can be
described as:
• A: Very good
• B: Good
• C: Acceptable
• D: Insufficient
• E: Very poor
Table 5.
CO2 concentrations during nap-time (GGD)
Legenda: A.R1[1], means Location A room 1
measurement session 1
The results from Table 5 were added up in Figure 7 and
Figure 8. In figure 7 and 8, the left column represents the
measurement position inside the crib attached to the bars,
the right column represent the measurement position at
the wall.
Figure 7. CO
2
concentrations during nap-time, all
measurements
However it is advised to take actions if this occurs too
much.
During the measurements in location B room 3, the
ventilation unit malfunctioned in the first nap-period.
When these values are excluded, see Figure 8, the CO
2
concentrations meet the conditions for class A and B for
85% (bars) and 85% (wall) of the time. It also can be seen
that the class A increases from 52% and 47% to 64% and
58%. The undesired class C is also significantly lower.
Figure 8. CO
2
concentrations during nap-time, Nap 1 B R3
excluded
The class D and E conditions also occur in both figures,
however this is a small percentage. During the test
period at the TU/e it was noticed that if someone is close
to the sensors, and breaths directly into the air intake, the
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values spike tremendously. As explained before, during
the experiment the children were put to bed, but where
not asleep directly. In some cases it was noticed that the
children would stand directly to one of the sensors,
especially the sensor attached to the bars.
In Table 4 it can be seen class D and E are most reached
during Nap 2 in location A room 2, these values are
displayed in Figure 7. During the end of the sleeping
period the values of above 1000 ppm are mostly reached.
Figure 9. CO
2
(PPM) vs. movement – Location A, room 2
4. Discussion and Conclusions
It should be noted that the results given here are only
applicable to the measurement period used in this
research: Summer. Measurements at another time of the
year, for instance during the winter, can lead to other
results and possibly to other conclusions because then the
natural supply of fresh air will be limited by the cold
outside temperature and danger of draft. The detailed
measurements of CO
2
concentrations within the breathing
zones of the babies, incidentally showed difference in
results caused by the location and the type of baby cot.
The measurement setup had to be installed in a practical
condition, the desirable measurement distance to the head
of an infant is 0.3m, at the researched location this was
significantly higher, around 0.4m (also depending on the
position of the baby). This to ensure the safety of the
infants, no measurement equipment could be placed
inside the cribs. The ventilation amounts that were applied
during nap-time, led to indoor air quality conditions that
met the guidelines of the Dutch Building Code and even
the more strict guidelines of local health authorities GGD.
The final classification for each investigated room is
calculated according the guidelines by the GGD (2006)
[15], therefore a percentile of 98% is taken into account.
The results are displayed in Table 6.
‘
B 3. – Nap 1’ can
be neglected due to the malfunctioning of the air handling
unit. However, this clearly shows the positive effect of the
applied mechanical ventilation system.
Table 6. Final classification (GGD) for each baby cot.in the
different rooms on the 2 locations A and B.
Location,
(sensor 1 and 2)
CO
2
[ppm]
Class
A.1. 514.7 A
A.2.-Nap 1 674.1 B
A.2.-Nap 2 681.4 B
B.3.-Nap 1 800.7 C
B.3.-Nap 2 590.1 A
B.4. 821.6 C
This article presents the results of CO2 concentrations
inside different baby cots of 2 day-care centers and shows
that the daycare facilities performed according to the
GGD classification. However there were increased CO2
levels by occupied cribs compared to empty cribs as well
as there was negative effects of specific location of the
cribs in the corner of rooms. Therefore, it is important to
do more research on the ventilation effectiveness inside of
the baby cots and not only on the ventilation rates in the
room in general. The effects can lead to CO2
concentrations which can be on average around 25% (with
in some situations even up to nearly 60% higher) than the
average concentrations in the sleeping rooms of the day-
care centers. This clearly shows the importance of these
factors and why it is not sufficient to just measure an
overall CO2-concentration as an indicator of the Indoor
Air Quality within day-care centers.
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