About 57.8 million people in Indonesia breathed unhealthy to hazardous air that month, AFP reported, citing a study released Oct. 29 by the Centre for Research on Energy and Clean Air (CREA). The think tank called the figure a record, up from a peak of 41.3 million in August.

CREA's estimate covers deaths within days of exposure to PM2.5, fine particles small enough to penetrate the lungs and bloodstream, which the World Health Organization has linked to a higher risk of illness and premature death.

Non-fire pollution from power generation, industry and transport caused a further 1,750 deaths, bringing September's total to 5,310, up 42% from about 3,740 in August.

Katherine Hasan, a CREA analyst, said the figures showed that pollution sources other than the fires were just as dangerous as the smoke, Republika reported.

In four provinces of Kalimantan, the Indonesian part of Borneo, air pollution deaths more than doubled to 1,470 from about 700 in August, with fire smoke behind 94-99% of them, the study found.

In five Sumatran provinces, deaths rose to 1,420 from 760, with smoke causing more than 90% of them in Riau, Jambi and West Sumatra.

A woman in a face mask pushes a wheelbarrow of used plastic bottles through thick haze from forest and land fires in Palangkaraya, Central Kalimantan, in late October. Photo by AFP

On Java, Indonesia's most populous island, deaths edged down to 1,530 from 1,570. Non-fire sources such as industry and vehicle emissions caused about 80% of deaths in West Java, Central Java, Jakarta and Banten.

Population-weighted PM2.5 exposure averaged 36 micrograms per cubic meter nationwide in September, more than seven times the WHO's annual guideline of 5 micrograms, about 10 times in Sumatra and 24 times in Kalimantan. The study said September marked the expected peak of dry conditions driven by El Nino.

Indonesia's Health Ministry said on Oct. 22 it had recorded 333,470 cases of acute respiratory infection in seven fire-hit provinces, nearly a quarter of them in children under 5.

CREA said President Prabowo Subianto had not declared the fires a national emergency despite calls from lawmakers, environmental groups and protesters, with officials arguing that regional capacity had not collapsed and task forces were still operating.

CREA suggested the government's reluctance may also stem from concern that a national declaration would make Indonesia liable for haze crossing its borders and hurt confidence in its palm oil, pulp and paper exports.

The International Monetary Fund projects the country's GDP at $1.48 trillion this year, the largest in Southeast Asia.

Responding to student protests on Oct. 28 over issues including the fires, Indonesia's government communications agency said it had deployed more than 72,000 personnel across six provinces to tackle the blazes, along with 2,106 health workers, and had distributed 5.3 million masks.

The smoke has also pushed up pollution levels in Malaysia, Singapore, the Philippines and Timor-Leste, Al Jazeera reported.

Rain in parts of Sumatra and Kalimantan in late October has brought some relief, The Star reported. Forecasters expect patchy showers rather than an abrupt change of season, and Indonesia's meteorological agency still listed five provinces, including South Sumatra and Jambi, at risk of fires through Oct. 31.