Suwido Limin was a longtime University of Palangkaraya professor who founded a volunteer firefighting brigade and spent two months in the field during last year’s haze crisis.

After the fires last year, his condition worsened, and he was diagnosed with cancer in February.

Limin, an ethic Dayak, also helped draft a regulation on indigenous rights in Central Kalimantan that has been submitted to the provincial government for approval.

Last year’s forest and peatland fire catastrophe is a memory now. But it may have claimed another life this week, with the passing of one of Indonesia’s foremost advocates for the environment and indigenous rights.

Suwido Limin, 61, died on Monday from a cancer colleagues believe was the result of years spent battling the annual fires and haze, which are caused by the large-scale drainage and drying of peat swamps for palm oil and timber plantations.

Limin’s health had deteriorated since late last year, when he spent two months fighting some of the worst fires yet with a volunteer brigade he founded, in his native Central Kalimantan province. In February, the longtime University of Palangkaraya professor was diagnosed with cancer.

“It feels like losing a parent,” said Kitso Kunin, field coordinator of the the Center for International Management of Tropical Peatlands, which Limin helped establish.

He died “because of the smoke,” added Kunin, a former student of Limin’s who later became his colleague. “Whenever there were fires, he was active in the field.”

Half a million Indonesians suffered from respiratory ailments during the 2015 crisis, according to the government, which said last October that 19 people had died from the haze.

The long-term health effects of exposure to the toxic fumes remain poorly understood, but scientists in Palangkaraya measured “extremely hazardous” levels of ozone, carbon monoxide, cyanide, ammonia and formaldehyde in the city where the haze turned the air a noxious orange color.

Limin, an ethnic Dayak, was born in Bawan village, in Central Kalimantan’s Pulang Pisau district, one of the most-burned last year.

He graduated from Lambung Mangkurat University in 1982 and went on to attend the the Bogor Agricultural Institute and the University of Hokkaido, where he earned a doctorate in peatland management in 2007.

Limin has been active in fighting the fires since 1997, when they were the most devastating. He was a fierce advocate of protecting peatlands, said Bernat Ripoll Capilla, co-director of the Borneo Nature Foundation, which worked with Limin for more than a decade.

“We are very said because he was very important in the study and conservation of peatlands in Kalimantan,” Capilla said. “He had very strong leadership.”

Limin was seen by many as a father figure at the University of Palangkaraya, where he undertook frequent collaborations with students. He helped secure protected status for the northern section of Sebangau Forest as the Natural Laboratory for the Study of Peat Forest, an important research area.

Bjorn Vaughn, a photographer who has lived in Kalimantan for seven years, worked with Limin during the 2015 disaster.

“I am moved by Suwido’s commitment as he and many others fought an impossible battle against the fires,” Vaughn said. “He had the biggest understanding of peat fires and how to prevent them, and I hope his message is heard.”

Limin also chaired a team to draft a regulation on indigenous rights in Central Kalimantan, an important part of the follow up to the landmark 2013 Constitutional Court ruling that gave indigenous peoples control over their customary territory.

“It wasn’t infrequent that he’d stay in his office until night,” said Simpun Sampurna, director of the Indigenous Peoples Alliance of the Archipelago’s branch in the province. “We did a lot of work together.”

The regulation has yet to be approved by the Central Kalimantan government, Sampurna said. He added that he would remember Limin for his perseverance and energy.

“Being friends with him was inspiring. It showed me that if we are consistent, we can accomplish a lot.”