Spatial analysis of oxygen and CO2 concentration across Gili Iyang — the 'oxygen island' (3 citations).
Click any dot on the map to select a measurement site. Toggle between O₂ and CO₂ to see spatial concentration patterns across Gili Iyang.
Gili Iyang has marketed itself as an “oxygen island” tourism destination, attracting visitors seeking health benefits from the island's reputedly pristine air quality. However, quantitative verification of these air quality claims was lacking — no systematic measurement of oxygen and CO2 concentrations had been conducted across the island.
Understanding the spatial distribution of oxygen and carbon dioxide concentrations is essential for validating tourism marketing claims, identifying optimal locations for wellness facilities, and monitoring environmental changes as tourism activity increases. Without empirical data, the island's environmental reputation rests on anecdote rather than evidence.
The study addresses this gap by conducting comprehensive measurements at 77 sites across the island's 9.15 km² area, using portable gas analyzers with GPS logging to create the first spatial map of O2 and CO2 distribution on Gili Iyang.
The study deployed portable gas analyzers across 77 measurement sites covering the full 9.15 km² area of Gili Iyang. Sites were selected to represent three distinct environmental zones: dense interior vegetation, coastal areas influenced by sea breeze patterns, and settlement zones with human activity.
Measurements were taken during both morning and afternoon periods to capture diurnal variation in gas concentrations. Each site was logged with GPS coordinates, enabling spatial correlation of O2 and CO2 levels with vegetation density, proximity to coastline, and distance from tourist activity zones.
Data analysis employed GIS-based spatial interpolation to generate continuous concentration maps across the island. The results were compared against standard atmospheric reference values (20.95% O2, ~415 ppm CO2) to quantify the island's deviation from baseline.
Average O2 concentration across all 77 sites was 20.02%, slightly below the standard atmospheric level of 20.95%. Average CO2 was 475.68 ppm, above the pre-industrial baseline of 280 ppm but within typical ranges for vegetated populated areas.
The spatial analysis revealed clear zone-based patterns. Interior forest areas showed the highest O2 concentrations (averaging 20.25%) and lowest CO2 (435 ppm), consistent with active photosynthesis in dense vegetation. Coastal zones showed moderate values influenced by sea breeze mixing. Settlement areas exhibited the lowest O2 (19.72%) and highest CO2 (532 ppm), reflecting human activity impacts.
Higher O2 concentrations correlated strongly with dense vegetation areas in the island's interior. Coastal areas showed more variation, influenced by diurnal sea breeze patterns that mix marine and terrestrial air masses. These findings provide the first empirical basis for Gili Iyang's environmental marketing claims.
A systematic grid of 77 measurement sites was established across the 9.15 km² island, stratified by environmental zone: interior forest, coastal perimeter, and settlement areas. GPS coordinates were recorded at each site for spatial analysis.
Portable electrochemical gas analyzers were used to measure O2 (range 0-25%, resolution 0.01%) and NDIR sensors for CO2 (range 0-5000 ppm, resolution 1 ppm). Instruments were calibrated against reference gases before each measurement session.
Morning (06:00-09:00) and afternoon (14:00-17:00) measurements captured diurnal variation. Each site was measured for 3-5 minutes after sensor stabilization. Environmental conditions (temperature, humidity, wind) were recorded alongside gas readings.
GIS-based inverse distance weighting (IDW) interpolation generated continuous O2 and CO2 surface maps. Zone-level aggregation enabled statistical comparison between interior, coastal, and settlement areas. Pearson correlation quantified relationships with vegetation indices.
Duplicate measurements at 10% of sites verified instrument repeatability. Cross-validation against the Mauna Loa atmospheric CO2 baseline and standard atmospheric O2 reference ensured data quality. Outliers beyond 3σ were flagged and re-measured.
Raw sensor readings were corrected for temperature and pressure using the ideal gas law. GPS coordinates were projected to UTM Zone 49S for distance calculations. Statistical analysis was performed using R with spatial packages.
Note: This section describes the measurement methodology used in the field study. No source code was involved — this is a pure environmental science paper based on direct instrument measurements and spatial analysis, not a software project.
AIP Conference Proceedings, 2022
DOI: 10.1063/5.0194116
Same research program on Gili Iyang Island — comprehensive renewable resource assessment.
Shared solar resource assessment methodology for renewable energy system sizing.
Provides the instrumentation foundation for environmental measurement and data collection.
Part of a broader research program on Gili Iyang's environmental and energy characteristics. This air quality characterization work supports sustainable tourism development and environmental monitoring on the island.