Associations between individuals’ daily carbon footprints and exposures to air pollution, noise, and greenspace in space and time

• Carbon footprints of people’s daily activities varied across spatial and temporal contexts. • Activities at home and nighttime have the highest estimated carbon footprints. • Carbon footprints positively correlate with PM 2.5 , which is particularly strong at home. • Carbon footprints have mixed associations with noise across spatial and temporal contexts. • Carbon footprints also have consistent negative associations with shrubland and woodland. To mitigate the catastrophic impacts of climate change, many measures and strategies have been designed and implemented to encourage people to change their daily behaviors for a low-carbon society transition. However, most people generate carbon emissions through their daily activities in space and time. They are also exposed to multiple environmental factors (e.g., air pollution, noise, and greenspace). Changing people’s behaviors to reduce carbon emissions can also influence their multiple environmental exposures and further influence their health outcomes. Thus, this study seeks to examine the associations between individuals’ daily carbon footprints and their exposures to multiple environmental factors (i.e., air pollution, noise, and greenspace) across different spatial and temporal contexts using individual-level data collected by portable real-time sensors, an activity-travel diary, and a questionnaire from four communities in Hong Kong. The results first indicated that individuals’ carbon footprints of daily activities varied across different spatial and temporal contexts, with home and nighttime having the highest estimated carbon footprints. We also found that activity carbon footprints have a positive association with PM 2.5 , which is particularly strong at home and from morning to nighttime, and mixed associations with noise (positive at home and nighttime, while negative in other places and during travel, from morning to afternoon). Besides, carbon footprints also have consistent negative associations with shrubland and woodland across different spatial and temporal contexts. The findings can provide essential insights into effective measures for promoting the transition to a low-carbon society .