Screen Shot 2016-11-10 at 6.32.40 PM.png“In December 1873, London was blanketed for a week in a yellow fog so thick that people could not see their feet. “Ladies & gentlemen,” Mark Twain said in a public lecture at the time, “I hear you, & so know that you are here — & I am here, too, notwithstanding I am not visible.”

Some 780 people died and 50 prize cattle on display at the Smithfield Club panted, wheezed and eventually died of asphyxia. Still, it took 83 more years of noxious air before the country passed the Clean Air Act in 1956.

This history, described in “London Fog: The Biography,” is a lesson in just how difficult it is for governments to put public health first when it comes into conflict with economic development, the political power of industry and even the polluting habits of their people.

The government of India is up against all of those things. The capital, New Delhi, a sprawling city of 20 million, just lived through an extraordinary episode of air pollution that closed schools for three days. India is one of a number of middle-income countries, including China, grappling with pollution problems that have ballooned along with economic growth and rapidly expanding cities.

A decade ago, the scope of the problem was poorly understood because the numbers on air pollution levels and deaths were spotty. But that has changed. Satellites have given scientists far more detailed pictures, allowing them to perform ever more precise calculations.

“Scientists underestimated the scale of outdoor air pollution because we just didn’t have the data on what people were breathing globally,” said Joshua Apte, an assistant professor of environmental engineering at University of Texas at Austin.

They did not like what they saw. Air pollution is the fourth top cause of death globally, after poor diet, high blood pressure and smoking, with more than one in 10 deaths linked to it in 2015, according to the Global Burden of Disease, a vast data trove compiled by more than 2,000 researchers led by the Institute for Health Metrics and Evaluation at the University of Washington.

The group estimates that roughly 6.5 million people died from both indoor and outdoor air pollution in 2015. Two million of them died in India. Deaths from outdoor air pollution have risen to 4.2 million in 2015 from 3.5 million in 1990.

Without strong policy action, the death toll will only worsen as megacities mushroom, exposing ever greater numbers of people.

“It’s much worse in middle-income countries than ever before,” said Dr. Maria Neira, director of the Department of Public Health, Environment and Social Determinants of Health at the World Health Organization. “Fifty years ago, only a few cities had populations of more than two million. Today there are many.”

The highest numbers of deaths from outdoor air pollution are in China, India and Russia, according to the Institute of Health Metrics and Evaluation. That is in part because they have the most people. The countries with the highest mortality rates — deaths from air pollution per 100,000 total deaths — are in Eastern Europe: Bulgaria, Ukraine, Belarus, Georgia and Latvia. The causes vary. Some believe it could be related to a legacy of dirty Soviet industry and fleets of aging diesel cars.

The key ingredient in policy change is a strong desire for it on the part of the population, said Christine L. Corton, the author of “London Fog”. In England, that happened in 1952, when another heavy smog episode — this time from coal-burning fireplaces and cooking ranges — left as many as 12,000 dead.

“In the end, it has to come down to the people wanting it,” she said.

Pollution seems like something that must have always provoked outrage, but in Britain that was not always the case. The famous London smog, etched into history by writers like Dickens and Impressionist painters such as Monet, Turner and Whistler, was once a symbol of prosperity, Dr. Corton said. It signified home fires burning (in Dickens there are grim references to meager fireplaces with just a few lumps of coal) and thrumming factories.

“The 1952 smog was a real knock to the psyche,” she said. “People had been through so much — the war, the Blitz. People said we didn’t go through all those deprivations to die from coal smoke. They were fed up. They wanted a better quality of life.”

As for India, Professor Apte said he believed public opinion had shifted, and that there was a much broader recognition of air pollution as a problem. He hopes comprehensive health data from hospitals is collected from this recent episode. That could take the issue out of the realm of abstract statistics and make it real.

“We might be reaching a tipping point with this Delhi smog episode,” he said.

Professor Apte, who has been working in Delhi for the past eight years and was there this week, said he has done work showing that incremental declines in pollution levels in very polluted places do not bring big health improvements, a phenomenon that might make change hard at first. But there are big benefits to longer-term pollution control.” The New York Times. Read it on

A Lesson for India in a Fog So Thick It Could Kill a Cow