The effect of environmental factors in urban forests on blood pressure and heart rate in university students

The forest experience can improve visitors' well-being even after a short time of walking in minutes. The effect of physical factor changes in urban forests on blood indices has not been well determined. In this study, 13 university students (7 males and aged 21 years old) were recruited to visit birch (Betula platyphylla Suk.), maple (Acer triflorum Komarov), and oak (Quercus mongolica Fisch. Ex Ledeb) forests each for 1 h. Participants' systolic and diastolic blood pressures (SP and DP, respectively) and heart rate (HR) were measured before and after the forest experience. Microenvironmental factors of temperature, relative humidity (RH), photosynthetic photon flux density (PPFD), and spectrum ratios of red (R), green (G), and blue (B) lights were also monitored. Either SP or DP did not respond to forest bathing among forests with different tree species. The change of HR in maple and oak forest was higher than that in the birch forest. Initial values of SP, DP, and HR before forest bathing were negatively correlated with their changes in the forest. DP was also negatively correlated with PPFD before participants went in the maple forest. After forest bathing, DP was correlated positively with RH but negatively with temperature. In conclusion, light spectrum can affect the blood pressure with the corresponding changes of temperature and humidity during visiting urban forest by university students.