Verification of heat stress mitigation effects by UV parasols using UTCI observations and thermal sensory questionnaire survey

UV parasols are anticipated to serve as a personal method for mitigating heat stress, owing to their portability. Thorough validation of the effectiveness in mitigating heat stress requires participant experiments. We conducted meteorological observations and thermal sensory questionnaires to verify the effect of UV parasol in mitigating heat stress. To emphasize the distinctive features of UV parasols, we contrasted their effects with those of street trees. The meteorological observation findings demonstrated that UV parasols decreased the Universal Thermal Climate Index (UTCI) by 3.6 degrees C compared to direct sunlight, equivalent to approximately 56 % of the reduction achieved by street trees. However, results from the thermal sensory questionnaire survey indicated that the alleviation of heat sensation by UV parasols was only approximately 30 % of that provided by street trees. This limited effectiveness of UV parasols is primarily ascribed to their inability to adequately shield participants' entire bodies from solar radiation. The experimental outcomes obtained in this study are expected to contribute to the reduction of heat stroke incidents and the design of adaptation measures for climate change.