A Dynamic Assessment of Disparities in Greenspace Exposure from a Time and Age Perspective: Comparing Lockdown and Non-Lockdown Periods

Abstract

Urban greenspace has a profound impact on public health by purifying the air, blocking bacteria, and creating activity venues. Due to people’s different position, the greenspace exposure to different age groups changes at various times. In this study, we combined NDVI (normalized difference vegetation index) and GVI (green view index) green indices with mobile signaling big data to evaluate the greenspace exposure of 3 age groups in Shanghai at different times. A dynamic assessment model for greenspace exposure has been adopted in this study. April 2021 and April 2022 were selected as the study periods, representing the non-lockdown period and the lockdown period, respectively. The results indicate that greenspace exposure changes slightly during the lockdown period. During lockdown, the NDVI exposure in the age groups of 31 to 50, 51, and above was higher than that during non-lockdown. However, the NDVI exposure of people aged 0 to 30 during lockdown is lower than that during non-lockdown. The GVI exposure of people aged 51 and above is lower than that of the other age group. Whether it is under lockdown or not, from 8:00 to 17:00, the NDVI exposure showed a slightly higher value than at other hours. The value of GVI exposure fluctuates steadily during 6:00 to 24:00. This study enriches the evaluation dimensions of urban greenspace exposure.