ASHRAE Journal - September 2022 - 24

TECHNICAL FEATURE
FIGURE 7 Example of the exposure of the chef in Restaurant 1 as measured for the identified measurement
period (x-axis). For some peaks the chef's activity is indicated
20 000
18 000
16 000
14 000
12 000
10 000
8000
6000
4000
2000
Baking Bacon
& Hamburgers
Baking Bacon,
Fries, Chicken
Baking
Hamburgers
Serving Food
Panini
Hamburgers
Frying Fish
17:00:00
17:30:00
18:00:00
18:30:00
19:00:00
remain below 1 mg/m3 and with that provide better
outcomes than those presented by Shirin and Reddy.7
Nevertheless, in all restaurants the exposure is at least
50% of the time higher than the 24 hours WHO limit of
25 µg/m3. For most restaurants this is more than 75% of
the time in the breathing zone of the chef (Figure 8, left),
but this level is often also higher at 3.3 ft (1 m) from the
stove (Figure 8, right). Figure 8 also shows that the exposure
for the different restaurants varies. Though it is
not possible to distinguish the exact cause for the different
outcomes, it is assumed that besides the cooking
behavior of the chef, the type of dish being prepared
also influences the particle generation. All the food discussed
in Figure 7 was prepared by the same chef, so it
hints at the link between cooking activity and particle
generation.
1200
1000
800
600
400
200
19:30:00
20:00:00
Figure 9 provides two examples
measured in two restaurants (No. 3
and 7). The exposure, presented in
boxplots, is compared at the different
positions in the kitchen and restaurant.
The outcome clearly shows
that exposure in the breathing zone
(BZ) of the chef is highest compared
to other positions in the kitchen and
the restaurant. From that it may be
concluded that the source indeed is
the cooking activity and that the ventilation
hood is able to remove part of
the generated particles.
If we ignore the peaks from the exposure measured
at the BZ of the chef, it is possible to correlate the concentration
at the BZ with that in the kitchen for all
restaurants together. Assuming a maximum of 75% of
the peak exposure for the BZ resulted in R2 = 0.57 (for
50%, R2 = 0.74). This would mean that the exposure in
the kitchen could be partly explained from the particle
concentration measured near the chef and the other
way around. As a result, one also may deduce that the
kitchen ventilation for the different restaurants investigated
in this field study operated at a similar performance
level.
To assess the importance of the peaks, Table 4 presents
a summary of the actual particle intake, per hour,
of the chef in each restaurant (assuming a 0.26 ft3/
min [7.5 L/min] breathing volume rate). It includes
FIGURE 8 Boxplot of the measurements in the breathing zone (left) and at 3.3 ft (1 m) distance from the stove (right) for the different restaurants.
WHO Limit
Well Limit
400
300
200
100
WHO Limit
Well Limit
PM Measurement (Chef Exposure)
PM Measurement (Kitchen 3.3 ft)
24
ASHRAE JOURNAL ashrae.o rg
S E PTEM B E R 2022
Concentration PM2.5 (µg/m3)
Breathing Zone PM2.5 Concentration (µg/m3)
#1 University
#2 Lunchroom
#3 Italian
#4 Dutch
#5 Irish Pub
#6 Asian
#7 Pancakes
Concentration PM2.5 (µg/m3)
#1 University
#2 Lunchroom
#3 Italian
#4 Dutch
#5 Irish Pub
#6 Asian
#7 Pancakes

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ASHRAE Journal - September 2022

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