2007, Piran, Slovenia

Acute and chronic heat exposure
ALLEVIATION OF HEAT STRAIN BY COOLING DIFFERENT BODY
AREAS DURING RED PEPPER HARVEST
Jeong-Wha Choi 1 , Myung-Ju Kim 1 , Joo-Young Lee 2
1 Seoul National University, Seoul, Korea
2 University of Minnesota, Minneapolis, USA
Contact email: leex3140@umn.edu
INTRODUCTION
One of the heaviest forms of farm work in Korea is the red pepper harvest in summer. The
direct sun light, lengthy working hours in a squatting position, the lack of a break, and
increased participation by elderly women have all been noted as problems in this work (Choi
et al., 2007). The fundamental method to alleviate worker’s heat strain is to reduce the
physical thermal burden through mechanization, and improved air-conditioning of
occupational fields. However, these ergonomic interventions are not feasible in red pepper
fields. Thus, we have developed personal cooling equipment (PCE) with different body
surface areas cooled, so that it is more practical for use in harvesting. The trunk is typically
cooled using a vest. The head and neck are known as more efficient areas to cool rather than
the trunk, arm, hands, leg, and feet (Cohen et al., 1989). The neck presented an advantageous
site for heat removal because of the proximity of large blood vessels to the skin in this area
(Shvartz, 1976). Based on previous studies, personal devices for cooling the trunk, neck, and
head have been developed. The aim of the present study was to examine the effects of
different types of personal cooling equipments (PCE) on the body’s heat storage, and the
alleviation of heat strain during red pepper harvesting, as simulated in a climatic chamber.
METHODS
Twelve young males (25.4 ±1.6 y, height 173.1 ±5.0 cm, 69.3 ±9.8 kg, 1.86 ±0.14 m 2 ) served
as volunteers. Written and informed consent was obtained. The experiment was undertaken
under eight conditions: (1) Control (no cooling), (2) Scarf A,( 3) Scarf B, (4) Hat (brimmed
hat with face shade and frozen gel on the neck), (5) Vest (cooling vest), (6) Hat+ScarfB, (7)
Hat+Vest, and (8) Hat+ScarfB+Vest. The surface area cooled by each condition is given in
Table 1. For cooling, frozen gel packs were selected. Subjects wore shirts with long sleeves,
long legged training pants, underwear, socks, work gloves, and athletic shoes. The garments
worn were based on farm workers’ work wear during the summer (Choi et al., 2007).
Table 1. Characteristics of personal cooling equipment (PCE)
Scarf
A
Scarf
B
Hat Vest Hat c) +
ScarfB
Hat+
Vest
Hat c) +Ves
t
+ScarfB
PCE total mass (g) 74 203 528 807 551 1,155 1,358
SAcooled (cm 2 ) a) 68 154 154 606 154 606 770
SAcooled (% ) b) 0.37 0.83 0.83 3.28 0.83 3.28 4.16
a) Surface area contacted by frozen gel packs; b) Percentage of SAcooled to body surface area; c) A gel pack excluded.
The environmental conditions of the climatic chamber were constant at a temperature of 33
±0.5 o C, 65 ±5% RH air humidity, and 39 ±1 o C black globe temperature (WBGT 33 o C). To
simulate the direct sunlight, appropriate lighting was fitted to the ceiling. Before entering the
chamber, subjects were fitted with sensors and donned experimental garments. After this, they
rested for 1 hour in another chamber, which was kept at a neutral temperature, and then
entered the heated chamber. Subjects simulated the red pepper harvest work based on a
previous study (Choi et al., 2007). The work lasted 120 min (50min harvest work + 10min
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