Mapping the Night Sky:
Investigating the Spatial Link Between Human Settlements and Light Pollution in the Philippines
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What is light pollution?
What is light pollution?
Light pollution, defined as the excessive or misdirected artificial light that brightens the night sky, has become a significant environmental issue in recent decades. This phenomenon not only obscures our view of celestial bodies but also disrupts ecosystems, affects human health, and contributes to energy wastage. The rapid expansion of urban areas and the increasing global population have been identified as primary drivers of this escalating issues.
When night arrives in the Philippines, millions of lights turn on, making the country’s brightness visible from outer space. Even though this bright display shows how far the country has advanced, it also points to a growing concern about light pollution that most Filipinos are not aware of. The purpose of this analysis is to answer a key question that links environmental science, urban planning, and public health: How does light pollution (night-sky brightness) vary across Philippine cities and rural areas, and how does it relate to urbanization? By using statistical methods and visual tools, this study will show the amount of artificial night lighting in the country and how it relates to population and urban growth.
Light Pollution in the Philippines: Using Data to Highlight an Unnoticed Environmental Problem
Light Pollution in the Philippines: Using Data to Highlight an Unnoticed Environmental Problem
Light Pollution as an Increasing Problem in the Philippines
Light pollution is a new environmental issue that influences many areas of life on Earth (National Geographic Society, n. d.). In the Philippines, this trend has become much stronger in recent years because of fast urbanization and economic growth. The need to study light pollution is important for more than just astronomy. It includes important problems of human health, protecting nature, energy use, and sustainable development that affect millions of Filipinos. This question needs to be addressed quickly because there is strong scientific evidence that too much artificial night lighting causes several problems. Because of light pollution, people often experience sleep problems, are more likely to develop certain cancers, and have various health issues related to metabolism (Davis et al., 2023).
The World Health Organization considers shift work that disrupts circadian rhythms to be a likely cause of cancer and urban light pollution has the same effect on residents exposed to artificial light all night (Palomar-Cros, 2024). In addition to harming people, artificial lights upset the behavior of many living things, including migrating birds and turtle hatchlings and this can lead to reduced biodiversity (Chepesiuk, 2009). What makes this question particularly relevant to contemporary Philippine society is the country's position at a critical juncture of development. The Philippines is seeing a fast increase in urban living and by 2030, the urban population is expected to grow by 67%, bringing 34.8 million more people into the country’s urban areas (Asian Development Bank, 2014). Because of this shift, cities are adding more artificial light as they develop, business districts grow and rural land is turned into suburban areas.
Simultaneously, the Philippines boasts some of the world's most biodiverse ecosystems and has traditionally served as an important location for astronomical research and education. Because there is a conflict between building and protecting nature, understanding light pollution patterns is important for making good decisions in policy. The situation today is troubling: many cities in the Philippines, mainly Metro Manila, Cebu, and Davao, now face light pollution like large cities worldwide and rural regions are following in their footsteps without considering the environment (Bautista et al., 2021). Although satellite images reveal a huge rise in nighttime lighting across the islands, this increase happens mostly outside the scope of regulations or the public’s notice (Villanueva, n. d.). Very few Filipinos know that the glow in the night sky is a serious environmental issue that must be addressed urgently.
If the problem is not dealt with, the Philippines could be headed toward permanent environmental damage and the loss of many chances for sustainable development. If light pollution is not controlled, the country may lose all its remaining places free from light pollution which is important for science, tourism, and nature. Light pollution wastes a lot of energy and drives up electricity bills in a country where costs are already high, while the loss of dark skies means missed opportunities for astro-tourism, a new industry that has helped develop other countries (Escario-Sierra, 2022). Besides, not dealing with light pollution allows environmental injustices to continue, as communities that suffer the most from too much artificial lighting, often low-income people near factories and busy roads, cannot speak up as much (College of Science - University of the Philippines Diliman, 2022).
Given these concerning trends, it is imperative to investigate the relationship between population growth and light pollution. Understanding how urbanization and demographic changes contribute to this phenomenon is crucial for developing effective mitigation strategies. This study aims to analyze recent data on population dynamics and light pollution levels to inform policies that promote sustainable urban development and environmental conservation.
The continued unchecked growth of light pollution also undermines the Philippines' commitments to international environmental agreements and sustainable development goals, particularly energy efficiency and biodiversity conservation (Lyytimäki, 2025). Here, we use statistical approaches and visual tools from descriptive statistics to make satellite data and demographic information easier for the public and policymakers to understand. By comparing the link between how urban areas develop and the amount of light pollution, this study seeks to suggest ways to support both growth and nature. The findings will contribute to the growing knowledge needed to develop effective "dark-sky" policies and promote sustainable lighting practices that benefit human communities and natural ecosystems throughout the Philippine archipelago.
Research Questions
What do we hope to discover through this study?
What is the relationship between population density and radiance levels across municipalities?
How do radiance levels vary across the major regions of the Philippines—Luzon, Visayas, and Mindanao?
How is night sky brightness spatially distributed across the country?
What is the frequency distribution of radiance levels across municipalities?
Scope of The Study
Scope of The Study
This study aims to map and analyze the spatial link between human settlements and light pollution in different parts of the Philippines using satellite data and demographic information. In particular, it looks into how the population density in urban and rural areas is related to fake radiance levels and how the night sky brightness changes across Luzon, Visayas, and Mindanao. The study is limited to the national level and doesn't look into specific local cases, how policies are put into place, or direct health reports. For this project, descriptive statistics and data visualization are used to look at satellite images and population data and find big trends and insights. The time period of the study is up-to-date (most recent datasets), and no direct data collection (like field observations) will be done. The study also looks at differences in light exposure across space by finding the areas with the most and least light pollution. This helps show how the environment is different depending on social and geographic factors. This study also aims to find new trends of how artificial light spreads in peri-urban areas, where people from rural areas are moving into cities and seeing more artificial lighting, even though they don't have all the infrastructure of cities yet. The study also looks into how the grouping of high-radiance areas can be explained by spatial analysis methods. This could point to areas with a lot of new construction or lighting that isn't managed.
Significance of the Study
Significance of the Study
This study is significant because it looks at light pollution, a new environmental problem in the Philippines that is often ignored. Through data and maps, this study raises awareness about the effects of too much artificial lighting that can't be seen. This helps with sustainable development and guides public and policy action.
Urban planners and Local Government Units (LGUs)- The data can help them plan cities better and choose lighting systems that are good for the environment and don't pollute the air with too much light. In line with eco-friendly lighting standards, this can help with making zoning laws, building projects, and urban renewal programs.
Environmental Policy Makers - The results back up the creation of "dark sky" laws and policies for lighting that uses less energy at both the local and national levels. The study's findings could be used as proof to support including light pollution in national environmental plans and changes to the law.
Public Health Officials- Understanding how excessive lighting affects sleep and health can help in creating healthier living environments, especially in densely populated areas. By linking light pollution data with population centers, health agencies can better target interventions related to circadian rhythm disruption and mental health.
Astronomical and Educational Institutions- The data can help protect dark-sky places that are important for studying the stars, stargazing, and teaching science, especially as the popularity of astro tourism grows.This can support the identification and preservation of potential stargazing sites and inspire curriculum development in schools and observatories.
General Public and communities – By raising awareness, the study empowers individuals and communities to advocate for better lighting practices that protect health, biodiversity, and energy resources.The data can be used by communities to demand changes to the way lights work in their areas, take part in citizen science, and take action on the environment at the local level.
Research Design
Research Design
This research uses a quantitative, descriptive, and correlational research method to look at how light pollution, which is measured by how bright the night sky is from space, changes across Philippine municipalities and how it is connected to urbanization, especially population density. The study will use secondary data from VIIRS radiance maps and the Philippine Statistics Authority to look at trends of artificial lighting using scatter plots, box plots, histograms, and choropleth maps. With these visual tools, you can find patterns and changes in light exposure across Luzon, Visayas, and Mindanao. The study's goals are to give data-driven insights and suggest actions, like "dark sky" laws, energy-efficient lighting policies, and promoting astro tourism, to help with sustainable urban planning and reduce light pollution. There will be no collection of original data, and all analysis will be based on datasets that are available to the public. This will make sure that the way we deal with a new environmental problem is both ethical and practical.
Statistical Presentations
Statistical Presentations
1. Scatter Plot of Population Density vs. Radiance Levels per Island Group
The scatter plot shows positive relationship between population and radiance levels across the three major island groups of the Philippines. Luzon, with the highest population of over 52 million, has the highest average radiance level (2.30). In contrast, Mindanao and Visayas, which have significantly lower populations compared to Luzon (approximately 26 million each), show much lower average radiance levels (0.18 and 0.11 respectively). This suggests that regions with higher population density tend to have increased levels of light pollution, likely due to more urban development, infrastructure, and human activity concentrated in those areas.
2. Regional Box Plot Analysis (Comparing Island Groups)
The regional box plot shows us a clear difference in light pollution among the three major island groups of the Philippines. Luzon has the highest median radiance, with values that are significantly skewed due to the radiance of the National Capital Region (NCR) being 14.47, exceeding all other regions in Luzon and is therefore an outlier. However, even without this outlier, Luzon still shows elevated radiance values due to other urbanized regions such as CALABARZON and Central Luzon. Visayas and Mindanao, on the other hand, show lower and more consistent radiance values with median values close to zero. In Visayas, Eastern Visayas has the lowest radiance value, being 0.11, while Central Visayas has the highest, being 0.29. In Mindanao, BARMM has the lowest radiance, being 0.04, while SOCCSKSARGEN has the highest, being 0.17. Seeing as how the highest radiance values of regions in Visayas and Mindanao are still significantly less than the regions with the highest radiance values in Luzon, we see that the three island groups have stark differences in terms of light pollution. We see how urbanization and population density in Luzon contribute to its higher radiance, whereas the less industrialized and more rural landscapes of Visayas and Mindanao have a much lower radiance.
3. Choropleth Map of Night Sky Brightness
Based on the chloropleth graph, we can observe the stark differences in light pollution geographically, among the different regions of the country. It is clear that NCR (National Capital Region) stands out the most being the only blue region in a sea of red, with a radiance value of 14.47, far surpassing all other regions and indicating extreme light pollution due to its extremely dense population and high levels of urbanization. CALABARZON and Central Luzon follow, with radiance values of 0.79 and 0.49 respectively, reflecting the spillover effects of urban sprawl and industrial activity from NCR. This is evident as they are the two regions next to NCR, and are of a lighter pink compared to the rest of the regions in the map. These three regions form a highly light-polluted area in Luzon. In contrast, most other regions, such as Central Visayas, Western Visayas, and Davao, show moderate radiance levels, while MIMAROPA (0.0172), BARMM (0.0383), and Zamboanga Peninsula (0.0468) have the lowest, indicating minimal artificial lighting and thus some of the darkest skies in the country. This graph suggests that the light pollution in the Philippines is heavily concentrated in and around cities that are highly urbanized and highly populated, while many rural and island regions remain relatively unaffected.
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4. Histogram of Regional Radiance Values
The Histogram of Regional Radiance Values gives an easy-to-understand picture of where artificial night lighting occurs in the Philippines, as measured in VIIRS radiance units (nanoWatts/cm²/sr). The horizontal axis includes all the main Philippine regions, from NCR to BARMM and the vertical axis shows the total radiance for each region, allowing us to see how brightly different areas are lit up. The histogram stands out because of its right-skewed distribution, with NCR shining brightest at 14.4699 nanoWatts/cm²/sr. In contrast, the remaining sixteen regions cluster within a remarkably narrow range near zero, with most values falling below 1 nanoWatts/cm²/sr. CALABARZON (Region IV-A) and Central Luzon (Region III) represent the next highest contributors, yet their values pale in comparison to NCR's overwhelming dominance.
NCR's exceptional radiance levels reflect the concentration of Metro Manila's 13,484,462 residents within just 636 square kilometers, creating the highest population density in Southeast Asia. This mega-urban center generates light pollution equivalent to major global cities like Tokyo or New York, while simultaneously representing less than 0.2% of the country's total land area. The presence of many low-radiance regions on the map shows that most of the Philippines, including BARMM, Northern Mindanao, and Davao, still enjoy clear night skies. This bimodal-like pattern, though technically unimodal due to NCR's dominance, suggests a dual development trajectory where mega-urbanization occurs alongside preserved dark-sky areas, creating opportunities for sustainable lighting policies and astro-tourism development.
5. Population vs. Radiance Deviation Plot per Region
The Population vs. Radiance Deviation bar graph shows Philippine regions where light pollution significantly exceeds expectations based on population size, revealing different influences on radiance levels aside from population density. The National Capital Region (NCR) stands out with the highest positive deviation (+10.41), as expected, due to the extremely high levels of commercial and urban activity in the region. However, we observe other regions that also have relatively higher positive deviations, such as the Cordillera Administrative Region (CAR) and Caraga, with +1.07 and +0.60, respectively. These positive deviances stem from localized factors. In the case of CAR and Caraga, these factors are likely to be a combination of tourism-related lighting, industrial and mining operations requiring night light, and possibly looser regulations on outdoor lighting compared to more urban and metropolitan areas. CAR is also a tourist hotspot, with tourist spots such as Baguio City, Mountain Province, and Sagada. From this, we can infer that due to these numerous localized factors, these regions' radiance levels are higher than expected for their population sizes.
Conclusion
Conclusion
By analyzing light pollution throughout the Philippines, we have found important links between urban growth and artificial night lighting which can guide policy decisions and support sustainable development. A clear and significant link between population density and light pollution in the Philippines is shown by the descriptive statistical analysis conducted here. The data shows that Luzon has the highest average radiance level at 2.30 nanoWatts/cm²/sr, compared to Visayas (0.11) and Mindanao (0.18). The big gap in average nighttime light levels proves that urbanization is linked to more artificial lighting. The National Capital Region's extreme outlier status, with a radiance value of 14.47 nanoWatts/cm²/sr, represents a critical finding that illustrates how mega-urbanization can create light pollution levels comparable to major global metropolitan areas.
A histogram of the radiance values across all seventeen regions clearly shows that most are close to zero, except for NCR which is far higher than the rest. The pattern shows that light pollution in the Philippines is very focused in some areas, going against the idea of a gentle urban-rural change. The calculations of standard deviation highlight that there is a lot of variation in lighting methods across areas, even when developmental policies are similar. Comparing island groups using box plot analysis shows that there are big regional differences, not just in population. Although most highly urbanized areas are found in Luzon, the data shows that lighting practices vary widely within the island group.
CALABARZON and Central Luzon both exhibit moderate radiance levels (0.79 and 0.49) that suggest urban areas around NCR are spreading out. This research demonstrates that light pollution is both a result of population density and an indirect outcome of the economic impact of major cities. It is clear from the choropleth map that the places with the most light pollution are also the most crowded which shows that many Filipinos live under constant artificial night lighting. By contrast, BARMM (0.0383), MIMAROPA (0.0172) and Zamboanga Peninsula (0.0468) have very low radiance which proves the areas have dark skies and should be preserved. This analysis reveals local factors that play a big role in light pollution, aside from just population changes.
In the Cordillera Administrative Region (CAR) and Caraga, the radiance values are higher than expected because of tourism, mining and possibly weaker lighting rules. The results suggest that controlling light pollution should focus on economic activities, tourism development and rules, not just on demographic planning. This research shows that descriptive statistics are useful in environmental research and that several statistical tools can effectively be applied to analyze data. Using all of these measures allowed us to learn much more about light pollution than we could from using just one type of analysis. The concentrated nature of light pollution was easily seen in the graphs and histograms and the correlation analysis supported the hypothesis that urban areas have more artificial lighting.
Recommendations
Recommendations
Urgent Actions for Areas with High Pollution
Based on the statistical evidence demonstrating NCR's extreme light pollution levels, immediate implementation of comprehensive "dark-sky" ordinances should be prioritized for the National Capital Region and surrounding areas. They ought to require that streetlights direct their light downward, preventing any upward light that makes the sky glow. The local governments in these regions ought to set lighting rules that require environmental impact studies for major projects and determine the highest acceptable radiance for every type of zoning.
How to Protect Dark-Sky Regions
The discovery of many areas with very low light pollution is opening new doors for protecting the night sky and developing astro-tourism. BARMM, MIMAROPA and Zamboanga Peninsula ought to be made Dark-Sky Preservation Areas with clear plans to stop light pollution from spreading. For new developments, these regions should use tough lighting rules that include shielding for astronomical viewing and warm-colored LEDs with a color temperature of 3000K or lower to help protect wildlife and astronomy. Investing in astronomy tourism in these dark-sky zones creates new economic chances and still protects the environment. Together, provincial governments, astronomical groups and tourism departments should arrange designated stargazing sites that use minimal impact lighting to ensure safety and keep the night sky clear for visitors.
Linking energy efficiency with sustainable development
It has been identified through this analysis that the close link between high population density and light pollution found in cities means current methods of lighting are greatly inefficient and go against the main objectives of sustainable development. Metropolitan regions with substantial radiance ought to become dependent on well-controlled LED lighting that adapts brightness according to how many pedestrians and vehicles are around at any time. A technology-based system may cut energy usage by 40-60%, keeping safety levels the same. Assessing light pollution should be considered standard practice in environmental planning, just as air and water quality. The analysis shows that odd radiance levels in CAR and Caraga may be related to economic projects, so it is important to develop special lighting rules for them to avoid damaging the environment.
Using data for continuous monitoring and managing practices
The research here shows that light pollution monitoring systems can be maintained by continuous use of satellite images shared by the public. The Department of Environment and Natural Resources ought to make an annual report that uses both VIIRS radiance mapping and information from the Philippine Statistics Authority to monitor the situation and test the success of government measures. Local observatories and schools should be given support to create citizen science projects that check light pollution with ground-based instruments, adding to what we get from satellite images for use in smart management. Results for central tendency and dispersion give us first benchmarks for picking acceptable light levels and keeping track of how things are improving.
Development of economic incentives and the necessary rules for the industry
There is statistical proof of high levels of light pollution in cities, so companies in these areas could be given incentives to adopt energy-efficient lighting systems. Electric cooperatives and distribution utilities ought to lower rates for approved dark-sky-friendly lights and apply a surcharge for businesses that use too much energy at night. The results of our analysis should be included in revised building and zoning standards to set the maximum level of radiance. Higher light pollution should result in new construction projects requiring lighting to meet dark-sky rules and be reviewed regularly for improvements.
Coordination on a regional level and use of best practices
The differences found in the regional group analysis make it clear that regionally customized policies would be better than nationwide rules. Coordination efforts should be organized between the regions and Visayas and Mindanao can model the way toward sustainable lighting, while Luzon prioritizes working on remediation and pollution. Positive deviation analysis highlights that population density is not the only influence on light pollution and so each sector’s rules for tourism, productive uses and infrastructure growth are required. Groups that represent lighting designers, urban planners and electrical engineers should introduce certifications that support dark-sky-friendly ways and meet environmental protection laws. The data and findings from this study are important for making sound light pollution policies that require swift response and action from multiple authorities and companies.
Sources
Sources
Asian Development Bank. (2014). Republic Of The Philippines National Urban Assessment. https://www.adb.org/sites/default/files/publication/42817/philippines-national-urban-assessment.pdf
Bautista, R. A., Turalba, P. M., & Cabuguazon, J. J. (December 6, 2021). Evaluation of light pollution awareness and residential lights in Pasig City. Journal of Biodiversity and Environmental Sciences , 19(6), 30-37. https://www.innspub.net/wp-content/uploads/2022/05/JBES-V19-No6-p30-37.pdf#:~:text=Notably%2C%20the%20increase%20of%20light,have%20a%20bright%20daylight%20condition.&text=Fig.,Light%20Condition%20outside%20their%20resident.
Chepesiuk, R. (2009). Missing the dark: health effects of light pollution. Environmental health perspectives, 117(1), A20–A27. https://doi.org/10.1289/ehp.117-a20
College of Science - University of the Philippines Diliman. (October 3, 2022). Impact of light pollution to local biodiversity. University of the Philippines Diliman. https://science.upd.edu.ph/impact-of-light-pollution-to-local-biodiversity/#:~:text=Light%20pollution%20affects%20the%20marine,but%20also%20reduce%20light%20pollution.
Davis, L. K., Bumgarner, J. R., Nelson, R. J., & Fonken, L. K. (2023). Health effects of disrupted circadian rhythms by artificial light at night. Policy Insights From the Behavioral and Brain Sciences, 10(2), 229–236. https://doi.org/10.1177/23727322231193967
Escario-Sierra, F., Álvarez-Alonso, C., Moseñe-Fierro, J. A., & Sanagustín-Fons, V. (2022). Sustainable Tourism, Social and Institutional Innovation—The Paradox of Dark Sky in Astrotourism. Sustainability, 14(11), 6419. https://doi.org/10.3390/su14116419
Lyytimäki, J. (2025). Sustainable Development Goals relighted: light pollution management as a novel lens to SDG achievement. Discover Sustainability, 6(197). https://doi.org/10.1007/s43621-025-00991-7
National Geographic Society. (n. d.). Light pollution. https://education.nationalgeographic.org/resource/light-pollution/
Palomar-Cros, A., Deprato, A., Papantoniou, K., Straif, K., Lacy, P., Maidstone, R., Adan, A., Haldar, P., Moitra, S., Navarro, J. F., Durrington, H., Moitra, S., Kogevinas, M., &Harding, B. N. (2024). Indoor and outdoor artificial light-at-night (ALAN) and cancer risk: A systematic review and meta-analysis of multiple cancer sites and with a critical appraisal of exposure assessment. Science of The Total Environment, 955, 177059. ISSN 0048-9697. https://doi.org/10.1016/j.scitotenv.2024.177059.
Villanueva, C. M. S. (n. d.). Community Engagement for Environmental Lighting and Acoustics in the Manila’s Univerisity Belt. https://press.ierek.com/index.php/Resourceedings/article/view/457/xml#:~:text=In%20the%20Philippines%2C%20the%20Housing%20and%20Land,the%20lighting%20systems%20are%20now%20not%20functioning.
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