ASHRAE Journal - September 2022 - 20

TECHNICAL FEATURE
FIGURE 4 Indicative measurements of the PM2.5 concentrations at 0.8 ft (0.25 m) (left) and 6.6 ft (2.0 m) (right) from the stove at maximum ventilation (during the highest
exhaust setting of the hood for the different cooking procedures).
50
45
40
35
30
25
20
15
10
5
Hamburgers C1
Pancakes C1
Chinese Wok C1 Hamburgers B1
WELL Limit
IAQ Kitchens
WHO Limit
Daily Average
Exposure
50
45
40
35
30
25
20
15
10
5
Time From Start Preparation Of Meal (Seconds)
respectively, during the low ventilation setting.
In comparing the temperature during the different
cooking procedures, there is a clear difference between
the preparation of the hamburgers and the other cooking
procedures. Ambient temperatures at a horizontal
distance of 0.8 ft (0.25 m) from the grill exceed 122°F
(50°C), while these remain around 77°F (25°C) when
frying pancakes or stir frying. At a horizontal distance of
6.6 ft (2.0 m), there is still a clear difference in ambient
temperature between the cooking procedures.
The hamburger cooking procedure was carried out
four times to compare the two different hoods and the
two different ventilation settings of each hood. For both
hoods, the PM2.5 measurements in the breathing zone
confi rm that the ventilation system is less effi cient when
the " low " setting is used as compared to the " high " setting
(Figure 5). Especially when the effi ciency features of
the backshelf were switched off, PM2.5 rapidly increased
until a median value of 384 µg/m3 during part 2 (2nd
part B2 standard ).
In comparing the canopy and backshelf hood, both
with the highest setting (Table 2, #3 C1 vs. B1), the PM2.5
exposure in the breathing zone during the hamburger
cooking was slightly but signifi cantly higher during the
canopy cooking session as compared to the backshelf
cooking session . This is while the percentage of time
the PM2.5 concentration exceeded the WHO limit of
25 µg/m3 in the breathing zone was higher during the
backshelf (15%) as compared to the canopy (9%). In the
" low " setting, the canopy was more effective than the
backshelf hood (Table 2, #4 C2 vs. B2).
To test the repeatability of the measurements, the
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ASHRAE JOURNAL ashrae.o rg S E P T E M B E R 2 0 2 2
Hamburgers C1
Pancakes C1
Chinese Wok C1 Hamburgers B1
WELL Limit
WHO Limit
Daily Average
Time From Start Preparation Of Meal (Seconds)
fi rst part of both backshelf measurements were carried
out with the same settings (high). The results show that
there are no signifi cant differences between these two
measurements (Table 2, #5 B1 vs. B2). This implies good
repeatability.
Field Study
The objectives of the fi eld study were:
¥ To identify the typical PM2.5 exposure of chefs and
other staff in real-life professional kitchens. To investigate
the role of the background concentration on the
exposure of the chef.
The methodology used in the fi eld study portion of this
research focused on measurements in seven restaurants
in the Netherlands between November 25, 2019, and
FIGURE 5 Boxplots of the PM2.5 exposure in the breathing zone, per meal and
ventilation rate in relation to WHO limit.
500
450
400
350
300
250
200
150
100
50
Hamburger C1
Pancakes C2
Hamburger B1
Hamburger C2
Wok C1
Hamburger B2 (On)
Pancakes C1
Wok C2
Hamburger B2 (Off)
PM2.5 Concentration 0.25 m From Stove (µg/m3)
240
480
720
960
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480
720
960
1200
1320
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600
120
480
600
PM2.5 Exposure Breathing Zone Chef (µg/m3)
240
480
720
960
240
480
720
960
1200
1320
240
480
600
120
480
600
PM2.5 Concentration 2.0 m From Stove (µg/m3)

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ASHRAE Journal - September 2022

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