This supplement holds the reference tables, platform directory, glossary and verification links referenced throughout the brief and the monitor. Content is factual and sourced; the language is plain. If anything here is wrong, email and we will correct it.
Why this specific number matters more than the others.
PM2.5 refers to fine particulate matter with a diameter of 2.5 micrometers or less — roughly one-thirtieth the width of a human hair. Particles that small bypass the nose and throat, enter the deep lung, and cross into the bloodstream. Long-term exposure is associated with heart disease, stroke, chronic lung disease, lung cancer, and measurable reductions in life expectancy. Children, older adults, and people with existing cardiovascular or respiratory conditions are disproportionately affected.
Mixed-waste burning — particularly of plastics — emits PM2.5 alongside dioxins, furans, polycyclic aromatic hydrocarbons, and heavy metals. Standard low-cost PM sensors capture only the particulate portion. The toxic organic compounds released in the same plume are not measured by the instrumentation described in this document, and their absence from the record should not be read as their absence from the air.
Two scales are commonly quoted. The WHO Air Quality Guidelines (2021) set health-based targets: 5 µg/m³ annual mean, 15 µg/m³ 24-hour mean. These were revised downward in 2021 to reflect updated evidence of harm at lower concentrations. The US EPA Air Quality Index translates PM2.5 into a 0–500 scale with six public-health categories; its breakpoints are looser than WHO's, reflecting regulatory rather than purely health-based limits.
Throughout this document, "above WHO 24-hour" means the daily average exceeded 15 µg/m³ — a threshold that roughly 68% of days in the Kerobokan record cross, and roughly 92% of days in the Kopernik record cross.
| Standard | PM2.5 Level | Classification |
|---|---|---|
| WHO 2021 · Annual | 5 µg/m³ | Long-term target |
| WHO 2021 · 24-hour | 15 µg/m³ | Daily exposure limit |
| WHO Interim Target 4 (IT-4) | Annual 10 / 24-hr 25 µg/m³ | Transitional benchmark |
| US EPA · Good | 0 – 9.0 µg/m³ | Satisfactory |
| US EPA · Moderate | 9.1 – 35.4 µg/m³ | Acceptable; sensitive concern |
| US EPA · Unhealthy (sensitive) | 35.5 – 55.4 µg/m³ | At-risk groups affected |
| US EPA · Unhealthy | 55.5 – 125.4 µg/m³ | Everyone may be affected |
| US EPA · Very Unhealthy | 125.5 – 225.4 µg/m³ | Health alert |
| US EPA · Hazardous | 225.5+ µg/m³ | Emergency conditions |
The places where a resident, visitor, or researcher can see Bali's air without relying on this page.
The most complete Indonesia-specific dataset. Six live Bali stations spanning Ubud and greater Denpasar, refreshed roughly every fifteen minutes, with PM2.5, PM10, temperature and humidity. The mobile app offers push notifications when readings cross thresholds; the same data is publicly accessible via the Nafas Foundation's live feed.
nafas.co.id →Aggregates private sensors worldwide. Bali coverage comes primarily from private households and businesses that have registered devices. Interactive map with forecast overlay.
iqair.com →Community-sensor network. Two Bali units have been reporting continuously for 687 and 728 days respectively. Raw CSVs downloadable from the map.
map.purpleair.com →Global aggregator of government and community sensors. Historical CSVs for Kerobokan and Denpasar KLHK remain downloadable even though both are currently offline.
aqicn.org →Open-data platform. Four Bali AirGradient units are listed (Ubud Rozendal, Balangan, two Kopernik / Ubud units). All are currently offline. Their historical CSVs remain downloadable.
explore.openaq.org →Indonesia's Ministry of Environment and Forestry air-quality portal. Only Kabupaten Badung is returned in Bali searches. The Denpasar station appears internally as Sedang dalam perawatan.
ispu.menlhk.go.id →Above 35 µg/m³, close windows and use an air purifier if available. Above 55 µg/m³, avoid outdoor exercise. Children, older adults, and people with respiratory conditions should take additional precautions at any reading above the WHO 24-hour guideline of 15 µg/m³.
Seven consecutive days from a sensor in East Bali, away from the south-west waste corridor. Daily averages sit in the moderate band; daily maxima reach the "Unhealthy for Sensitive Groups" range.
| Date | Daily Avg PM2.5 | Daily Max | Daily Min | EPA Category |
|---|---|---|---|---|
| Apr 7 | 22.3 | 64.8 | 5.0 | Moderate |
| Apr 8 | 30.1 | 87.1 | 10.1 | Moderate |
| Apr 9 | 33.1 | 84.7 | 7.6 | Moderate |
| Apr 10 | 19.7 | 53.2 | 11.6 | Moderate |
| Apr 11 | 25.1 | 51.9 | 13.4 | Moderate |
| Apr 12 | 27.8 | 93.5 | 7.3 | Moderate |
| Apr 13 | 21.9 | 56.8 | 8.1 | Moderate |
Daily maxima of 50–93 µg/m³ enter the "Unhealthy for Sensitive Groups" range. These peaks indicate intermittent pollution events even in areas distant from the Denpasar waste corridor. Without additional sensors, it is not possible to determine how widespread these events are.
Every claim in the brief and the monitor can be checked at its original source. The links below are the receipts.
The terms used throughout this site, defined.