ASHRAE Journal - September 2022 - 17

TECHNICAL FEATURE
TABLE 1 Laboratory hood testing matrix.
*
NO.
#1
#2
#3
#4
#5
#6
#7
#8
NAME COOKING APPLIANCE; PRODUCT COOKED HOOD TYPE
C1
C2
C1
C2
C1
C2
B1
B2 ON
B2 OFF
Gas Charbroiler; Hamburgers
Gas Charbroiler; Hamburgers
Gas Range; Pancakes
Gas Range; Pancakes
Gas Range; Stir-Fried Vegetables
Gas Range; Stir-Fried Vegetables
Gas Charbroiled; Hamburgers
Gas Charbroiler; Hamburgers
aCapture and Containment
normally functioning kitchens of restaurants in the
Netherlands.
In both, the investigators included factors that may
infl uence exposure levels, like the type of food that is
prepared, layout and characteristics of the kitchen,
exhaust hood characteristics, overall ventilation setting,
etc. During the fi eld study we wanted to explore the
actual PM2.5 exposure of chefs and staff in professional
kitchens in the Netherlands. Results from a research
study7 conducted for professional kitchens indicate that
these levels are orders of magnitude higher than what is
generally regarded as safe.
Laboratory Study
The objectives of the laboratory study were:
* Identify the PM2.5 exposure of a chef in an ideal
situation (in terms of ventilation).
Canopy
Canopy
Canopy
Canopy
Canopy
Canopy
Backshelf
Backshelf
HOOD AIRFLOW
(FT3/MIN/FT)
352
C&Ca value
200
307
C&Ca value
200
307
C&Ca value
200
123
C&Ca value
123
C&Ca value
AIR CURTAIN STATUS
On
On
On
On
On
On
On
1st Part: Effi ciency
Enhancement On
2nd Part: Effi ciency
Enhancement Off
Investigate the effect of different
cooking techniques on PM2.5
exposure concentrations.
*
Investigate the effect of different
ventilation settings on the PM2.5
exposure of a chef and concentrations
in the kitchen.
In this laboratory portion of the
study, the PM2.5 exposure was monitored
for different cooking processes
and for different exhaust ventilation
airfl ows. The measurement locations
included the breathing zone of the
chef and the indoor air in the space
close to the stove or grill. Table 1 provides
an overview of the various test
conditions.
All were tested with the canopy
FIGURE 1 Visualization of the hood characteristics. Left: Picture of the setup of the canopy hood. Right:
Illustration of a backshelf hood with enhanced efficiency features.
hood in two different settings. The fi rst setting (C1) was
the canopy hood at " capture and containment " (C&C)
value (exhaust levels that are suffi cient to remove visible
vapors under the given load). The C&C values were
determined using schlieren thermal imaging to ensure
capture on the front and sides of the exhaust hoods.
During the second setting (C2), the canopy was reduced
to an airfl ow of 883 ft3/min (1500 m3/h). A photo of the
canopy hood setup is shown in Figure 1.
Additionally, the backshelf hood (Figure 1, right) was
tested in two settings when cooking hamburgers. The
fi rst setting was at C&C value (B1), and during the second
setting (B2), the hood was allowed to spill halfway
into the cooking procedure. Dimensions of the canopy
hood were 53 in. (1350 mm) long by 63 in. (1600 mm)
deep installed at a height of 79 in. (2000 mm) above
the fi nished fl oor. The length of the backshelf hood was
43 in. (1100 mm).
PM2.5 concentrations were measured
at three locations (Figure 2):
breathing zone of chef (PM2.5 sensor
type I); 0.8 ft (0.25 m) from the
stove/grill (PM2.5 sensor type II); and
6.6 ft (2.0 m) from the stove/grill
(PM2.5 sensor type II). For the measurements
in the breathing zone, a
tube was connected to the inlet of
the measurement device. The other
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ASHRAE Journal - September 2022

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