Denpasar air quality around 18–19 September shows elevated PM2.5

Denpasar — Air quality monitoring platforms reported moderate to poor pollution levels in Denpasar around 18–19 September 2026, with fine particulate matter (PM2.5) identified as the main concern for sensitive groups.

AccuWeather’s air-quality page for Denpasar listed PM2.5 as the principal pollutant and described local air quality as poor, advising sensitive individuals to reduce time outdoors if they experience breathing difficulties or throat irritation. The service characterises this category as unhealthy for sensitive groups, meaning people such as children, older adults and those with asthma or other respiratory conditions may feel symptoms earlier than the general population.

An independent forecast from Norwegian-based air-quality service Airmine classified overall air quality in Denpasar as fair on 18 September 2026, with its composite AQI indicator at 38.3 out of 100 and pollution peaking around 10:00 local time. Airmine’s breakdown showed fine and coarse particles as the main contributors to pollution on that day.

PM2.5 as the main health concern

On AccuWeather’s Denpasar page, PM2.5 is highlighted as the key pollutant driving health risk for sensitive groups. These particles are small enough to penetrate deep into the lungs and can enter the bloodstream, and AccuWeather links exposure to coughing, breathing difficulties and aggravated asthma, as well as longer-term risks to the heart and lungs.

Airmine’s Denpasar forecast for 18 September similarly points to particulate pollution as the primary issue, with PM2.5 and other fine particles driving the AQI values during the morning peak. The service notes that air quality varies by time of day and emphasises that peaks do not necessarily represent conditions for the entire day.

How bad was the air?

While the draft figure of an AQI of 94 with PM2.5 at 28 µg/m³ on 18 September cannot be confirmed from the available live pages, both AccuWeather and Airmine indicate that air quality in Denpasar around that period was in the moderate-to-poor range, with conditions potentially unhealthy for sensitive groups at times.

IQAir’s Denpasar page, which aggregates readings from monitoring stations in Bali, reported a US AQI of 93 with a PM2.5 concentration of 31.4 µg/m³ as of 19 September 2026. IQAir classified this level as “moderate” and noted that PM2.5 concentrations were more than six times the World Health Organization’s annual guideline value. This supports the picture of elevated particulate pollution, though not necessarily at the exact level or time stated in the draft.

According to an early-September 2026 explainer on Bali air quality, south Bali locations such as Canggu, Seminyak, Kuta and Sanur were generally seeing readings in the “good” to “moderate” range during the wider regional haze episode, with Denpasar occasionally running higher because of traffic. That account cautioned that local peaks near busy roads do not significantly change island-wide averages.

Regional haze, but limited evidence of smoke over Bali

The broader region has been affected by severe haze driven by wildfires in Sumatra and Kalimantan during the 2026 dry season. Coverage of the crisis by international and specialist outlets describes hazardous air quality in parts of Indonesia and neighbouring countries, with smoke plumes travelling north-west toward Malaysia, Singapore and the Philippines.

An article focused on Bali’s conditions during this episode reported that, as of early September 2026, Bali was not covered in haze and that prevailing winds were carrying smoke away from the island rather than towards it. The same piece cited local environmental officials as saying that previous fog episodes over Bali had been linked to advection fog rather than smoke, based on satellite monitoring.

There is no indication in these sources that the forest-fire smoke causing hazardous conditions elsewhere in Indonesia was significantly degrading air quality over Denpasar on 18 September.

Data gaps and interpretation

AccuWeather notes that its air-quality information uses raw data supplied by Plume Labs and may not have undergone full quality-assurance review, warning that equipment limits and short-term fluctuations can produce inaccurate or invalid readings. The page does not identify the exact monitoring station or instrument in Denpasar, and the available data are presented as current or hourly values rather than a continuous time series for 18 September.

Airmine’s forecast likewise provides time-specific AQI and pollutant estimates but does not specify the precise sensor locations within the city. Without a clearly documented station, a time-stamped series of readings and comparison with Indonesia’s official monitoring network, the available figures provide a snapshot of conditions rather than a definitive description of air quality across Bali on that date.

Given these limitations, the confirmed data show that Denpasar’s air around 18–19 September was affected by elevated particulate pollution that could pose risks to sensitive groups, but they do not conclusively attribute the readings to local emissions, transported haze or specific short-term weather phenomena.

Sources

• AccuWeather - Denpasar Air Quality Index
• Airmine - Denpasar Air Quality Forecast
• IQAir Indonesia - Denpasar Air Quality Index and PM2.5 concentration
• Evarah Collection blog – "Is Bali Affected by the 2026 Haze? Canggu Air Quality"
• Vision Times – "Volcano and Wildfires in Indonesia Shroud Southeast Asia as Air Quality Falls to Hazardous Levels"
• BBC News – "Toxic haze spreads across South East Asia amid 'super' El Niño"