Every year, like clockwork, between June and November, a hazardous haze settles over swaths of Southeast Asia.

The haze originates in smoldering peatland wildfires on islands in Indonesia. Born of illegal slash-and-burn agricultural practices on palm oil and paper plantations, the fires can burn for months and are stanched for good only by seasonal downpours. Meanwhile, they spread pollution that turns the air a sickly sepia, and make it dangerous to breathe.

This year has been no exception. Drought conditions on the islands have produced an even worse than usual haze season: Half a million people have reported acute respiratory infections since July 1 in affected areas. A spokesman for Indonesia’s Meteorology, Climatology and Geophysics Agency called the haze “a crime against humanity.”

Indonesian President Joko Widodo, popularly known as Jokowi, met with U.S. President Barack Obama on Monday in Washington — the leader’s first official visit to the United States. He was slated to visit California on Wednesday to meet with Apple’s Tim Cook and other tech leaders but said he would cut short that leg of the trip due to the haze crisis, which has gotten even worse over the past two days. Indonesia is preparing for a mammoth government push to assist people in the worst-hit area, potentially evacuating thousands of babies and young children in Borneo and Sumatra. The United States has pledged $2.75 million in assistance.

Indonesia has laws against land clearing by fire, but the practice is rampant and has proven nearly impossible to eradicate in provinces like Riau, in Sumatra, where plantations provide wealth and employment and where local corruption makes the law difficult to enforce.

Jokowi has promised to rein in the haze but says he needs more time. The fires, which often burn unchecked in remote forested areas, are difficult to fight because they burn underground in flammable peat soil as well as above the surface. Environmental activists have recorded extensive destruction this year in some of the world’s most biodiverse, endangered rainforest ecosystems. Indonesia has the third-largest primary rainforests in the world, after Brazil and Congo, and deforestation is proceeding at a faster rate in Indonesia than anywhere else. Over the years, companies like Asia Pulp and Paper that have provided products to Staples, Disney, and other U.S. corporations have faced criticism for their role in perpetrating the haze and destroying some of the final remaining habitats for Indonesia’s tigers and orangutans.

Beyond Indonesia, the haze has a long history of impact on Singapore — separated from Sumatra by the narrow Strait of Malacca — which for more than 40 years has been periodically blanketed by smog, forcing business and school closures. This year, winds have swept the haze into Malaysia, which shares a land border with Indonesia on the island of Borneo, and Thailand, a few hundred miles to the north, as well. The FINA Swimming World Cup in Singapore and a marathon in Kuala Lumpur, the Malaysian capital, were both canceled, and regional officials have been highly critical of Indonesia’s response to the crisis. Earlier this month, Jokowi announced he would accept international firefighting aid, and Singapore was quick to provide aircraft. Australia, China, Malaysia, Russia, and South Korea have pitched in as well.

However, it is still Indonesians — mostly in Sumatra and Borneo — who feel the harshest impact of the haze emerging in smokey plumes from their backyards. And many Indonesians, including environmental activists, argue that their neighboring countries shouldn’t be so quick to blame Indonesia for the problem because they share culpability. “Of course all the fires are coming from Indonesia, but Singapore is enjoying the ‘deforestation economy’ of Indonesia as a financial center,” Bustar Maitar, the global leader of the Indonesia Forest Campaign at Greenpeace, told the New York Times, “and there are many Malaysian palm oil companies operating in Indonesia, and Singaporean companies are there as well.”

At times, fires have burned at well over 1,000 hotspots. This month, Riau began evacuating babies younger than six months old, due to their particular sensitivity to air quality. Earlier this month, Republika, a large Indonesian newspaper, drew attention to the issue by hazing out its front page to the point of near illegibility, with the headline: “Student Victims of Haze Forced to Go to School,” and the caption, "When covered with smoke, all the news becomes difficult to read.”

With monsoons due in November, the hazy season will soon give way to the rainy season. But without changes in the way companies pursue wealth in Indonesia, the annual haze-ing ritual will continue.

Above, Indonesian police and firefighters blast water onto the fires burning in Central Kalimantan, Borneo, on Sept. 24.

A motorcyclist travels through the haze on a road in Palemband, Sumatra, on Sept. 30.

A villager tries to extinguish a peatland fire on the outskirts of Palangkaraya, a city in Central Kalimantan, Borneo, on Oct. 26.

Indonesian President Joko Widodo inspects a burned expanse of peatland in Southern Kalimantan, Borneo, on Sept. 23.

A man carries his son as they pass by fires on the way to their house in Palembang, South Sumatra, on Oct. 2.

An Indonesian teacher and her students wear face masks to filter out pollution in Palembang, South Sumatra, on Oct. 8.

People play badminton while wearing face masks in Pekanbaru, the capital of Riau, one of the worst-hit provinces in Sumatra, on Sept. 13.

A Singaporean Chinook helicopter, capable of pouring water from a huge hanging bucket, arrives at an air force base in Palembang, South Sumatra, on Oct. 10, as part of a joint regional effort to tamp down Indonesia's fires.

Indonesians praying in Pekanbaru on Sept. 15.

Cyclists race through a town in West Sumatra on Oct. 6, as they compete in Indonesia's annual Tour de Singkarak.

A man dressed as spiderman, who was set to participate in Singapore's Pink Ribbon Walk for breast cancer, which was cancelled due to the haze, hangs from a railing on Oct. 3.

A man splashes water on a fire near his house in Palembang, South Sumatra, on Oct. 3.

A firefighter repositions a hose as he and others put out fires near a village near Palembang, South Sumatra, on Oct. 2.

Indonesian soldiers hose off smoldering peatland outside a village in Palembang, South Sumatra, on Oct. 2.

A member of Indonesia's National Disaster Management Agency checks on the progress of a water-bombing operation in Pelalawan, Riau, on Sept. 17.

A woman and young boy walking through Pekanbaru, Sumatra, on Sept. 13.

Malaysian children play in a river as schools remain closed due to hazy conditions in Hulu Langat, near the capital of Kuala Lumpur, on Oct. 6.

A firefighter stands amid a raging fire in South Sumatra on Sept. 12.

A helicopter carries a bucket of water over South Sumatra on Sept. 3.

Firefighters combat a fire in South Sumatra on Sept. 5.