Effectiveness and Acceptance of Cooling Vests Among Couriers in the Express Delivery Industry

Status:

ongoing

Aims:

Because of climate change, the number of days with temperatures exceeding 30°C and the frequency of heatwaves have already increased in Germany. It is anticipated that there will be an additional five to 15 days per year with temperatures above 30°C by 2050. These periods of high temperature are particularly challenging for those engaged in outdoor work. If the body is unable to regulate its temperature through sweating when external temperatures are elevated, the body will overheat. Potential outcomes of this include circulatory failure, muscle cramps and heat-related illnesses such as sunstroke or heat stroke.

Cooling vests can be used as a personal protective measure to reduce physical stress in hot weather. They use active or passive cooling mechanisms to stabilize body temperature and prevent overheating. However, cooling vests are rarely used in professional contexts.

To promote the use of cooling vests, field studies in various work areas are necessary. A project is evaluating the feasibility of a study on the effectiveness and user acceptance of cooling vests among courier drivers. The study aims to quantitatively assess the effects on body temperature and performance to determine the suitability of the methodology and the use of cooling vests, laying the groundwork for further research.

Activities/Methods:

In the study, at least 5 courier drivers from express delivery services wear the hybrid cooling vest Bodycool Hybrid during work. To activate the vest, it is moistened with water and cooling packs are inserted. The ambient temperature should be at least 25°C throughout the working hours. Comparative measurements without the cooling vest are conducted with the same couriers on days with similar temperatures.

At the beginning of the work shift, the resting heart rate as well as the skin and core body temperature of the couriers are measured while sitting (duration 10 minutes). The data is recorded using a chest strap (HRM-Pro) and sensor (CORE) from Garmin and logged with a smartwatch (Garmin Forerunner 965). The CORE sensor for recording cory body temperature is worn on the skin and measures the heat transfer between the body and the environment. An AI-based algorithm uses this data to calculate core body temperature. Previous studies have demonstrated the validity of this method by comparing it with invasive body temperature measurements. For example, measurements with electronic capsules that are swallowed and measure core body temperature in the digestive tract were used as a comparison.

During the work shift, skin, and core body temperature as well as heart rate are continuously recorded. Additionally, the distances and altitudes covered are tracked using the GPS of the smartwatch. A thermohygrometer measures the climatic conditions (Wet Bulb Globe Temperature, air temperature, relative humidity) at 5-minute intervals at a stationary location.

After the work shift, the couriers evaluate the user acceptance of the cooling vest, their physical exertion, and their thermal sensation using questionnaires. Open-ended questions are used to identify positive and negative aspects of the cooling vest and the study design. During the completion of the questionnaires, a final resting measurement of skin and core body temperature as well as heart rate is conducted (10 minutes).

For evaluation, the working heart rate, the average heart rate reserve, and the percentage of time above the individual endurance limit are determined from the measured heart rate. Differences in the recorded variables between measurements with and without the cooling vest are examined using descriptive statistics and hypothesis tests.

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