Officials have implored the people of New Delhi to stay inside, indefinitely. Five million children in India’s capital have been handed face masks. Everyone is to keep windows closed. Contrary to the most fundamental medical advice, the city’s chief minister urged residents this week to “avoid outdoor physical activities.”

News images seem cut from an apocalyptic outbreak film. One of India’s holiest rivers is covered in toxic foam that looks like white cotton candy. Midday visibility is like a foggy dusk. The air reportedly causes people’s eyes to burn.

At the root is not some panic-inducing virus, though. The cause is simply pollution from agriculture and transportation. And the city’s air crisis is unique only in degree. The same elements are accumulating in the air everywhere.

More than a decade ago, a study by India’s government predicted the untenability of the air in New Delhi, warning that the crisis was primarily due to emissions from the city’s more than 8 million cars. Since then, New Delhi’s air has constantly been among the world’s most dangerous, and it has recently gone through phases of being simply uninhabitable. This happens often in the weeks when nearby farmers set their fields ablaze after harvest, adding to an already precarious baseline of smog from burning fossil fuel.

Automotive and industrial emissions fill the air with nitrogen, sulfur dioxides, and “black carbon,” the latter of which includes tiny particles that penetrate deep into the lungs. Over the past days, levels in New Delhi have exceeded 10 times what the U.S. Environmental Protection Agency deems safe. (The idea that any level is “safe” is disputed, as even very low levels have been found to cause disease.) The effect is lethal, in India and beyond. Air pollution is the leading cause of premature death in parts of the world. It already accounts for more than a quarter of deaths from lung cancer and heart disease, according to the World Health Organization. A Lancet study found that particulate matter alone killed some 1.9 million people in Asia in 2015. In some parts of China, one in 20 deaths is due to bad air.

The episodes, which are getting worse over time, presage crises in other urban areas around the world. Half of the world’s cities do not meet the World Health Organization’s safety standards. Even for people who can afford to stay indefinitely indoors, that way of living has its own consequences for health, from sedentary behavior to social isolation.

The New Delhi air crisis is reaching peak severity in the same week that the U.S. formally notified the United Nations that it would be the only country among 196 signatories to withdraw from the Paris Agreement on climate change. In the 2016 agreement, almost every country in the world committed to establishing its own emissions target. Secretary of State Mike Pompeo said in a statement on Monday that the commitment to sustainable energy posed an “economic burden.”

Year after year, the economic effects of the world’s current environmental path are bearing out in New Delhi. Flights are canceled and schools closed. Car owners are limited to driving only on certain days. Construction is stalled, and hospitals are flooded with disease, as they will be flooded with chronic effects in coming decades. People miss work, become disabled, and exit the workforce. They consume more medical care and rely on safety nets.

This is the economic future that the status quo invites. Even for the world’s wealthiest people, who may be able to guarantee their personal air and food supply, their stability will be contingent on the billions of people around the world who still have to go outside.