Two students working in the Longcore Lab @ UCLA in the Sustainable Los Angeles Grand Challenge Undergraduate Research Program (URSP) have had presentations accepted to the Undergraduate Research & Creativity Showcase at UCLA Undergraduate Research Week. Here are their abstracts:
Characterizing Nighttime Light Exposure Across Land Use and Demography
Ahalya Sabaratnam and Travis Longcore
As outdoor lighting transitions from older lighting types to high-efficiency LEDs, there is a growing need to develop an understanding of the impacts of artificial light at night (ALAN) on human health, ecosystems, and environmental justice. The impacts of light pollution may be felt by all humans, but certain populations are experiencing greater effects based on factors such as race, ethnicity, and socioeconomic status. Whereas remotely sensed data is currently used to describe ALAN exposure for epidemiological studies, a method is needed to characterize neighborhood differences in a replicable manner. This study compares and analyzes outdoor nighttime settings in a sample of neighborhoods stratified by socioeconomic characteristics using multiple methods. Quantitative data gathered includes satellite data from DMSP and VIIRS to determine upward radiance, along with instantaneous illuminance measurements in 6 directions at road intersections in low-density residential, high-density residential, and commercial/mixed-use areas of Westwood Village, California. Qualitative data documents lightscapes through a 360-degree camera to convey what it is like for a human to move through these areas. Resulting maps and visualizations show variations in streetscape light exposure by land use. The findings show a correlation between median income, higher socioeconomic status, and lower nighttime light exposures. Stratified analyses reveal that inequity based on light pollution varied in a residential-commercial context.
Quantifying the Contribution of Outdoor ALAN to Ambient Indoor Illumination
Jules de la Cruz and Travis Longcore
The biological effects of artificial light at night (ALAN) have become an area of concern as research correlating outdoor ALAN to adverse health outcomes has increased. The majority of such research quantifies individual ALAN exposure through either satellite estimations or ground-based measurements. Each method has its advantages and limitations, but an untested assumption present in both is the 1:1 ratio of measured outdoor ALAN to the indoor luminous environment. The intricacies of this ratio are a necessary consideration to light exposure approximations, as the exact biological thresholds of human photoreceptors to LAN are not yet fully understood. This research investigated the quantitative relationship between outdoor ALAN and indoor illumination by analyzing overnight low-light measurements within residences in Los Angeles. Two twilight photometers were placed a uniform distance apart near bedroom windows to collect obtrusive outdoor ALAN and its resulting contribution to indoor illumination 1.5 feet away. The resulting ratios of outdoor ALAN causing indoor illumination was found to vary depending on environmental factors such as window geometry and building height, with values ranging from 0.09 lux – 0.85 lux. The findings of this research demonstrate that the relationship between outdoor and indoor LAN varies depending on environmental and architectural factors. This may be an important element of consideration for epidemiological studies when using either satellite or ground proxies for individual exposure to LAN.