Abstract: The purpose of this thesis is to examine the body of evidence concerning light pollution and exposure to artificial light and determine if the scientific research warrants regulatory oversight in the United States. The first question that guided this effort was: Does improper artificial lighting and exposure to light-at-night constitute a risk to human health and safety? The follow up question being: Is light pollution a concern to ecological systems, and if so to what extent? A comprehensive literature review was conducted to ascertain the status of the research—if any—in these two areas and what the findings were. The overarching purpose of this thesis was to answer the primary question: Does the scientific research on light pollution and exposure to light-at-night exposure make a case for regulatory oversight, within the mandate of the EPA? The questions were illuminated by conducting a thorough literature review, doing an informal email survey, and by in-depth interviews with people researching artificial light and with individuals in the EPA. The study concluded that there is no ready consensus to be reached in this area. Such a disparate topic as light pollution does not readily lend itself to an easy answer. However, the findings show that light pollution and light-at-night exposure do have some negative impact. This is especially true in regards to the night sky and the biota. Whether the EPA should be involved in regulating it is not entirely clear. Their mission statement leads one to presume that certain effects of light pollution do fall under their mandate. More research to quantify the effects of artificial light on humans is critically needed to show causation between artificial light exposure and health problems.

Abstract: In 2018, Solar Cycle 24 entered a deep solar minimum. During this period, we collected night sky brightness data at Cosmic Campground International Dark Sky Sanctuary (CCIDSS) in the USA (2018 September 4–2019 January 4) and at Aotea/Great Barrier Island International Dark Sky Sanctuary (AGBIIDSS) in New Zealand (2018 March 26–August 31. These sites have artificial-light-pollution-free natural night skies. The equipment employed are identical Unihedron SQM-LU-DL meters, used as single-channel differential photometers, to scan the sky as Earth rotates on its axis. We have developed new analysis techniques which select those data points which are uninfluenced by Sun, Moon, or clouds to follow brightness changes at selected points on the celestial sphere and to measure the brightness of the airglow above its quiescent level. The 2018 natural night sky was measured to change in brightness by approximately 0.9 mag arcsec−2 at both locations. Preliminary results indicate the modulations of the light curves (brightness versus R.A.) we observed are related in complex ways to elements of space weather conditions in the near-Earth environment. In particular, episodes of increased night sky brightness are observed to be contemporaneous with geomagnetic activity, increases in mean solar wind speed, and some solar proton/electron fluence events. Charged particles in the solar wind take days to reach near-Earth environment after a coronal hole is observed to be facing in our direction. Use of this information could make it possible to predict increases in Earth’s natural night sky brightness several days in advance. What we have learned during this solar minimum leads us to search for other solar driven changes in night sky brightness as the Sun begins to move into solar maximum conditions.

Abstract: Avian mortality at communication towers in the continental United States and Canada is an issue of pressing conservation concern. Previous estimates of this mortality have been based on limited data and have not included Canada. We compiled a database of communication towers in the continental United States and Canada and estimated avian mortality by tower with a regression relating avian mortality to tower height. This equation was derived from 38 tower studies for which mortality data were available and corrected for sampling effort, search efficiency, and scavenging where appropriate. Although most studies document mortality at guyed towers with steady-burning lights, we accounted for lower mortality at towers without guy wires or steady-burning lights by adjusting estimates based on published studies. The resulting estimate of mortality at towers is 6.8 million birds per year in the United States and Canada. Bootstrapped subsampling indicated that the regression was robust to the choice of studies included and a comparison of multiple regression models showed that incorporating sampling, scavenging, and search efficiency adjustments improved model fit. Estimating total avian mortality is only a first step in developing an assessment of the biological significance of mortality at communication towers for individual species or groups of species. Nevertheless, our estimate can be used to evaluate this source of mortality, develop subsequent per-species mortality estimates, and motivate policy action.