A bus fitted out with oxygen tanks is providing a sanctuary in a city on Indonesia’s Borneo island, where people are choking from forest-fire-induced haze and the blazes show no sign of letting up.

Indonesia regularly battles seasonal forest fires, predominantly on Sumatra and Borneo islands, but this year the infernos are the most intense in more than a decade.

An intense El Nino weather phenomenon has driven up temperatures, leaving the country’s vast forests and peatlands more vulnerable to fires that have turned skies orange across Indonesia, Malaysia and Singapore.

As respiratory illnesses increased in the Central Kalimantan city of Palangka Raya, the local government provided an “oxygen bus” replete with oxygen tanks and medical professionals who offer residents a chance to be hooked up to a small oxygen tube around their nose for five to 10 minutes at a time.

“The service is intended to help people access oxygen, particularly those experiencing respiratory problems or who need oxygen support amid unhealthy air quality conditions,” the Central Kalimantan provincial health department said on Instagram this week.

Indonesia’s air pollution index has shown some areas of Borneo and Sumatra registering pollution levels of over 1,000, with readings of 300 or more already categorised as hazardous.

Respiratory illnesses linked to the fires have risen, with about 350,000 cases from August to Sunday, according to the health ministry. Central Kalimantan, where the fires and the haze have been particularly bad, reported about 31,000 cases as of Sunday.

“This is a disaster from nature and there is not much we can do,” Oktawina, 44, who like many Indonesians goes by one name, said with an oxygen tube hooked to her nose.

Medical staff on the white-and-blue bus recorded patients’ details and administered oxygen to residents reporting breathing difficulties. One of them, Yuda, said most residents who came to the bus coughing or had trouble breathing.

Purnasari, 31, a patient on the bus, said: “If I’ve been out of the house lately I feel tightness and coughing … because this morning the thick yellowish smoke so my breathing feels tight.”Another beneficiary, Siti Jumiati, said she had long been battling red, burning eyes, a sore throat and a cough. “Today, on this bus, I can get help breathing for free,” she said.

The Southeast Asian country has for months struggled to contain fires that deforestation monitor Nusantara Atlas says have consumed more than 1.9 million hectares (4.7 million acres) in the nine months to September. The government has not confirmed or disputed the figure.

Amid diplomatic objections from neighbouring countries forced to breathe the foul air, patience has also been running thin at home, marked by sporadic anti-government protests.

Hundreds of students protested at the office of the provincial governor last week demanding a greater response to the fires, local news website Kompas reported.

The health ministry said it has set up nearly 500 facilities countrywide where people can access free oxygen and treatment for haze-related ailments. Nearly 300 of them are in Central Kalimantan.

At a nearby shelter run by NGOs in Palangka Raya, Alexandra Surya Habsari was treated with a nebuliser and oxygen for breathing difficulties and a headache.

“I’m really fed up, but I don’t even know who I’m supposed to be angry with … this is already way beyond what can be considered normal for a human being to endure,” she said.

The 43-year-old said her daily 20-minute commute to the office had become torture. “We’re supposed to be able to see the blue sky, breathe in oxygen, see the sun and enjoy clean air. But when it’s like this, what we’re breathing is poison,” she said.