Conclusions
This study was motivated by the need for refining the initial guidelines on working in
hot weather. The original heat stress model was considered as inadequate because it
utilized an overly simplified HI which is a mere function of temperature and relative
humidity to measure the thermal environment. The original model failed to express
the relationship between physiological response and other key components of
environmental variables, namely, radiation and air movement. WBGT is a more widely
used index of thermal indicator to take further account of sun and wind. An additional
variable, RHR is included in the enhanced model, improving the overall prediction
power of the original model. A refined and enhanced heat stress model is now
constructed to predict a worker’s physiological responses to different meteorological
factors, work-related factors, and personal factors. More specific heat stress guidelines
can be formulated based on objective and scientific parameters to safeguard workers’
health and safety.
Workers in different trade activities may have different degrees of susceptibility to
heat stress. A trade by trade specific study would better reflect the real situation.
Although this study applies specifically to the bar bending and fixing trade, more work
is needed to further investigate other trades and to other countries to provide a holistic
view in future. In the light of the enhanced heat stress model, a set of good practices
and indices, such as work duration, work-rest pattern, can be developed to ensure
the health and safety of site personnel working in hot weather. This would be of
tremendous value in better safeguarding workers’ health and safety by reducing the
occurrences of heat stress on site.