Indonesia's threatened orangutans are being choked by the haze from the land-clearing fires burning on the islands of Sumatra and Borneo, and being driven out of their habitat into farmland, where they risk being shot.
As with humans, the orangutans most at risk are the young.
At a rehabilitation sanctuary just outside of Palangkaraya, in central Borneo, 16 baby orangutans have been treated for smoke inhalation.
Six of the young orangutans suffered acute respiratory problems, said Monterado Fridman, from the Borneo Orangutan Survival Foundation at Nyaru Menteng.
"You do not see the effect straight away for the adults, but for babies you see the effect straight away," Mr Fridman told 7.30.
"They get flu, cough, and diarrhoea, and without intervention they collapse in one or two weeks.
"We reduce their activity and playtime outside, and they spend more time inside now, but if you bring them inside for a week or two they get stressed, because they are used to playing outside."
The foundation treats the young orangutans with rest, rehydration with the aid of a saline drip, and vitamins.
The smoke in this part of the Indonesian province of Central Kalimantan has been dense for three months.
Visibility at times is less than 50 metres, and the pollution is so thick that an estimated half a million people are suffering from acute respiratory problems.
The scale of this man-made disaster is immense.
One organisation, the Global Fires Emissions Database, estimates Indonesia has overtaken China and the United States to become the world's biggest polluter.
It is extraordinary for a nation without major heavy industry and where most people cannot afford to drive cars.
Teams from the Borneo Orangutan Survival Foundation have also been rescuing wild orangutans driven out of their habitat by smoke and fire.
So far they have brought five wild animals into the sanctuary.
"Generally they are experiencing malnutrition, dehydration, and hunger," Mr Fridman said.
"The orangutans whose habitat was burned are heading to people's farms where they can get food from the fruit trees planted by local people."
The foundation's team has to find the orangutans, tranquilise them, and then bring them back to the sanctuary. It is time-consuming and dangerous work for the rescuers and rescued alike.
Eventually they will be released back into the wild - when the fires are out.
Daily rainfall is improving conditions in parts of Kalimantan, but the haze is still thick and affecting both humans and orangutans.