The gender differences in the impact of solar radiation on thermal comfort of people engaged in outdoor activities

The urban outdoor thermal environment directly influences people’s willingness to be active and their quality of life. During outdoor activities, exposure to solar irradiance is unavoidable; variations in solar irradiance can markedly alter thermal perception and physiological responses, thereby giving rise to sex differences between males and females. This study employed controlled experiments to systematically examine sex differences between males and females in subjective thermal sensation and physiological responses during activity under varying levels of solar irradiance. Participants’ thermal sensation votes and physiological indicators were recorded continuously. The findings show that subjective thermal sensation increased significantly with higher solar irradiance. Under standing conditions, the highest mean thermal sensation vote at the strongest irradiance level reached +2.8 for males and +1.6 for females. Across all irradiance levels, females consistently exhibited higher skin temperatures than males, with a maximum between-sex difference of 0.91 °C. In addition, at all irradiance levels, females showed greater mean increases in systolic and diastolic blood pressure than males, with maximum between-sex differences of 3.13 mmHg and 3.75 mmHg, respectively. These results indicate that females are more prone to physiological heat stress under solar irradiance exposure, underscoring pronounced sex differences in thermal comfort.