Evaluation of heat stress of workers using wearable biosensors in protected horticulture

For sustainable horticulture, it is essential to protect the health and safety of farm workers.
In Japanese protected horticulture, environmental control technologies have been developed and spread.
Using such technologies, the number of companies that produce year-round production has been increasing, which also implies an increase in working hours performed in hot environments.
In Japan, the number of scorching days above 35°C has increased over the past decade.
Such high-temperature working environments are associated with an increased risk of heat stroke.
The Japanese Ministry of Agriculture, Forestry, and Fisheries (MAFF) has distributed a checklist for heat stroke prevention and lists checking wet bulb globe temperature (WBGT) as one of its measures.
However, in scorching environments that exceed body temperature, the conventional heat stress indicator, WBGT, cannot be applied as is, and there is little experimental evidence to support the application of traditional standards.
In this paper, we propose a group-based heat stress assessment method based on heart rate responses and show that it can be applied to protected horticulture situations.
Our study measures the heart rate, physical activity, and inside-clothing temperature of 25 female workers engaged in year-round tomato cultivation using wearable biosensors to assess the heat strain of the workers.
In addition, we measured the temperature in the greenhouse to evaluate the environmental heat stress.
Our results showed that the median heart rate of the group of workers was approximately ten bpm higher at all work intensities in scorching conditions with greenhouse temperatures above 35°C compared to temperatures below 24°C. Simultaneous heart rate monitoring of a workers’ group could be used for heat stress assessment because the heart rate increase is associated mainly with the core body temperature.

IV Asian Horticultural Congress – AHC2023

Y. Isoyama, M. Nakashima, M. Kaneko, K. Kiyono

biometrics, greenhouse, heat load, occupational health, quantile regression, thermal environment

https://doi.org/10.17660/ActaHortic.2024.1404.36