From The Optimist Magazine

Summer 2014

Forget the airpocalypse—the skies are getting cleaner. Hopeful signs from Mexico City, no longer the world’s dirtiest.

On a cool Saturday morning, I check the air quality report on Twitter before putting on my running shoes. “Good,” the tweet says—as it does nearly every morning. As I make my way to Viveros park, the mountains ringing the valley are sharply outlined. To my left rises the volcano Popocatépetl, 43 miles outside of town, its cap of snow clearly visible. On the tree-lined running track, I inhale a lungful of oxygen and smell the scent of moist foliage.

The location of this idyllic spot? Mexico City. That’s right: the metropolis the United Nations labeled the dirtiest on earth 20 years ago. In 1990, old cars and dirty industry belched so much smoke into the air that pollutant concentrations in the city exceeded recommended limits every day of the year. “Makesicko City,” writer Carlos Fuentes called it.

Humberto Bravo, one of Mexico’s pre-eminent air quality scientists, remembers those days well. The blanket of smog choking the capital got thicker every year. “My eyes used to water,” says Bravo, of the
Center for Atmospheric Sciences at the
National Autonomous University of
Mexico. “The collar of my shirt would even get dirty. In the early nineties, air pollution was apocalyptic.”

Today, a network of monitoring equipment scattered across the high valley -registers much better results: 2012 saw 248 clean-air days—and that’s under standards considerably stricter than those in place 20 years ago.

The city where, according to local legend, birds used to fall dead from the polluted skies now functions as a beacon of hope for residents of Asian cities who justifiably complain about air quality. Progress in the Western Hemisphere’s largest metropolis—Mexico City has more than 20 million inhabitants—proves that people don’t have to resign themselves to living in suffocating surroundings.

Today’s media coverage seems to tell a different story. The city of Harbin, China, experienced its own airpocalypse last fall. As temperatures dropped, coal-fired power plants went into overdrive, spewing even more soot than usual into the sky. “I can hardly see buildings 50 yards away,” one resident complained on the news. Schools closed; so did highways and airports. Chinese state media estimated the concentration of PM2.5 fine particles (those measuring 2.5 microns or smaller) in the dark blanket of smog to be 500 micrograms per cubic meter—20 times the level deemed safe by the World Health Organization (WHO). Others contended that the actual figure was double that. Visibility in the middle of the day was so poor, it might as well have been midnight.

According to a recent article in The Lancet, air pollution has for the first time become one of the 10 leading causes of death worldwide. In 2010, 3.2 million people died prematurely from breathing contaminated air, the journal reported. A decade earlier, the figure was 800,000. According to the Health Effects Institute (HEI), in Boston, which led the epidemiological study, particulate pollution causes strokes, heart disease, lung cancer and pulmonary infections.

Last fall, the European Environment Agency stated that 90 percent of European city dwellers were breathing dangerous air. A few days later, the International Agency for Research on Cancer (IARC) reported that studies showed that air pollution caused cancer. It cited tainted air as the disease’s most widespread environmental cause.

Yuck. (Cough, hack.) If you read the papers, the world appears to be experiencing one of its most deplorably polluted periods ever. But what can we learn from Mexico City’s monumental shift?

Air pollution is nothing new. Research on mummified tissue from ancient Egyptians and Peruvians indicates that even they suffered from blackened lungs, probably because of the indoor fires they lit to cook and keep warm. Then there was lead smelting, a heavy polluter since 5000 B.C.; deposits in the Greenland ice provide evidence.

Even the most prosperous, “civilized” places during those times endured toxic air. In the Roman Empire, houses, forges, potteries and other places of work emitted dark clouds of smoke, which the Romans called gravioris caeli: “heavy heaven.” Later, cities like London and Paris stank, not least because people simply dumped excrement on streets and in rivers. The switch from wood- to coal-fired heating only made matters worse.

“City air used to be much viler than it is now, particularly in the 19th century and the first half of the 20th,” says Wybren Verstegen, an environmental historian at VU University Amsterdam.

Two 20th-century disasters put today’s smog problems to shame. In October 1948, the town of Donora, near Pittsburgh, experienced a cold snap. Zinc and steelworks emissions mixed with smoke from coal-fired heaters and hung, trapped, above the town. Within four days, the hospitals were full of patients gasping for air. At least 20 people died, along with 800 animals.

The even more alarming Great Smog of London followed four years later. In the face of bitter cold, the city permitted the use of low-quality coal. But the weather stayed calm, so there was no wind to blow away the smoke. Wembley Stadium and theaters were forced to close. The BBC canceled broadcasts, since guests were unable to find the studios. Monitoring stations recorded 4,460 micrograms of PM2.5 fine particles per cubic meter—178 times today’s WHO limit. By the time the smog finally lifted, London had racked up almost 3,000 more deaths than in the same week the previous December.

The Donora and London events—with toxins like sulfur dioxide and soot present in concentrations hundreds of times higher than those today—led to the realization that heavy air pollution could be deadly. Clean-air efforts have been on the political agenda ever since. In 1956, four years after the London disaster, Parliament passed its first law restricting factory emissions and coal use. The United States adopted federal legislation in 1970. The European Commission followed two years later. The days when factories could pump out whatever fumes they liked, unfiltered, were over. Leaded gas was phased out. Catalytic converters and diesel particulate filters made cars cleaner still.

Governments like to take credit for positive environmental trends. In 2010, the Environmental Protection Agency (EPA) boasted of the successes it had achieved over its 40-year existence. The Clean Air Act had averted more than 200,000 premature deaths in its first two decades, along with 672,000 cases of chronic bronchitis and 843,000 asthma attacks, according to
the agency. And emissions of six common pollutants had dropped by more than 40 percent since 1990, while the GNP had more than doubled.

But some contend it’s wrong to give the authorities credit. “Air pollution had been dropping for decades before the federal government took over policy control,” notes Joel Schwartz, author of Air Quality in America. He cites a 75 percent drop in particulate readings in Pittsburgh between 1900 and 1970. Comparable measurements in Chicago, Cincinnati and New York also show that a decline in pollution was well under way by the time politicians began setting standards.

Meanwhile, in my hometown of Mexico City, things have steadily improved: Between 1989 and 2012, carbon monoxide levels fell by 79 percent, sulfur dioxide by 89 percent, and lead by more than 97 percent. In 2013, Mayor Miguel Ángel Mancera won international praise for the reversal.

In the United States, things have improved as well. Take Los Angeles, which had extremely poor air quality in the 1970s. Since 1990, lead has fallen by 88 percent, carbon monoxide by 79 percent, nitrogen dioxide by 56 percent. Today, the air in L.A. is even cleaner than in Manhattan—although New York also showed big improvements. Carbon monoxide there has fallen by 79 percent and sulfur dioxide by 75 percent, to name just two.

The future looks bright for air quality. So why is every report on the subject filled with doom and gloom? Joel Schwartz has an idea. “Regulators’ jobs and power depend on a public perception that air pollution is a serious and urgent problem,” he argues. “Regulators also set the level of the health standards, meaning that they get to decide when their job is finished. Naturally, it never will be.”

The Belgian epidemiologist and author Luc Bonneux suggests another reason for the apparent unanimity. “Critical academic minds have been driven away through harassment,” he says. “So the alarmists’ message dominates.” Plus, when filthy air suffocates a city, it’s news, but gradual improvement doesn’t warrant headlines. That’s how journalism works.

The smog in China’s cities looks to be a genuine but temporary problem, caused by the same rapid economic growth that should help to enable a cleanup before long. After all, as affluence in the West has increased, air pollution has been dealt with.

This prediction is supported by the environmental Kuznets curve, named after Nobel Prize winner Simon Kuznets. His theory holds that rising income is linked to reduced pollution. Though pollution initially increases with economic growth, it decreases once incomes hit a particular—albeit unknown—level. The mechanism obtains for water and air pollution and also deforestation: such trends are reversed when the economy reaches a certain size. The thinking is that as soon as the money and technology are there, people will demand a cleaner environment. While the theory has its skeptics, so far, the entire Western world seems to have followed the environmental Kuznets curve.

But is there reason for optimism for millions of Asians, with their face masks and their prodigious spending on home air purifiers? Will the curve hold true for centrally governed states like China? Verstegen, the Dutch environmental historian, points out that civil liberties have to be in place for pollution to be tackled. “The environmental Kuznets curve works only in democratic societies that have freedom of the press, free elections and freedom to organize,”
he argues.

And yet the Chinese government appears to be paying attention. Last year, Beijing unveiled an ambitious plan to limit coal use, make gasoline cleaner and take the dirtiest cars off the roads. Pre-2005 cars will be banned beginning next year. In the capital itself, all this should cut pollution by a quarter compared with 2012.

Here, too, Mexico appears to be setting an example. When Makesicko City started getting healthier, thanks in part to tougher regulations like those planned in China, the country was nevertheless being led by an undemocratic state party that had held power for 60 years.

Jacob Vaarkamp is well placed to compare the two nations: He lived in Beijing from 2000 to 2009, before moving to Mexico City. “People are always yelling about air pollution,” Vaarkamp sighs. “In Beijing, everybody complained about getting a sore throat in winter, and they’d blame the pollution. But when you have 10 percent humidity for months because it never rains, everybody gets a sore throat. That has nothing to do with pollution. Mexico City has gotten much cleaner. But then again, it does rain a lot more here, and that washes away pollution.”

With air quality, there’s always room for improvement. People like Humberto Bravo know that. In Mexico City, he’s among those who remain unsatisfied with the progress made to date. It’s true that ozone levels in the city are dropping every year, but not that fast, critics say. And while every car undergoes emissions checks, the rules for diesel trucks are far too lax.

In the West, too, the calls for cleaner air continue. But the question is how much it would cost to obtain additional health benefits, and whether that money wouldn’t be better spent tackling bigger problems. In 2012, on behalf of the Copenhagen Consensus Center, scientists compiled a list of urgent world problems that would benefit most from a $75 billion budget. Their list of the top 30 problems and actions doesn’t mention air pollution once. 

Edwin timmer, a correspondent in Latin America, is breathing easier these days.

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What is particulate matter?

“Particulate matter” is a generic term for various substances suspended in the air. These particles include innocent ones found in nature (such as sea salt and pollen, and others originating from volcanoes, dust storms, forest and grassland fires), but also substances such as soot from exhaust fumes. The exact composition of particulate matter varies by region and by day. And that’s one reason why studying its health effects is highly complicated.

There are also other reasons why studies aiming to demonstrate its dangers are shakier than the public realizes. On closer inspection, the HEI study in The Lancet citing 3.2 million -particulate-related deaths worldwide turns out to be constructed out of assumptions and -estimates. It also ignores toxicological tests showing that humans and animals are affected only by extremely high concentrations of particulates.

Some, including Tony Cox, a consultant and editor of the journal Risk Analysis, argue that the study was poorly designed. “They attribute deaths and illnesses to sources that do not necessarily cause them,” he says, “and they do not provide a logically or statistically sound basis for predicting what would happen if exposures were reduced. Millions of particulate deaths sound really scary, but they’re not an established fact.” | E.T.

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More cars = cleaner air?

Yes, if they’re fuel-efficient, Mexico City shows.

Some see it as a recipe for environmental disaster: a billion Chinese, each with a car of his or her own. Mexico City, however, demonstrates that the rapid growth of a nation’s fleet can actually help the environment. When the United Nations named the Valley of Mexico the most polluted place on earth 20 years ago, more than three million cars were at large on the capital’s roads. By 2011 the number had reached eight million. Did the air in Mexico City get worse? Quite the contrary: Levels of carbon monoxide fell by 79 percent between 1989 and 2012, sulfur dioxide declined by 89 percent, and lead dropped by more than 97 percent.

The reversal won Mayor Miguel Ángel Mancera international plaudits in 2013. Government policy played an important role in the cleanup. Dirty industrial sites, including a refinery belonging to oil company Pemex, were relocated out of the valley. Polluting buses were swapped for natural-gas-powered ones. Only cars under five years old are allowed on the roads daily; older ones have to stay parked one or more days per week. The Ecobici bike-rental scheme, launched in 2010, expects a record 180,000 users this year.

Cars are getting cleaner not just because politicians want them to, but because technology is making it possible, and consumers are
choosing greener, more fuel-efficient models. In his book The Rational Optimist, journalist Matt Ridley wrote, “Today, a car emits less pollution travelling at full speed than a parked car did in 1970 from leaks.”  | E.T.