The Air in Nearly Every Big City in the Developing World Is Unhealthy to Breathe

Four out of five city-dwellers worldwide live in towns with lousy air, raising the odds of premature death from lung or heart ailments, the World Health Organization (WHO) reported Thursday.

Urban air pollution went up 8 percent in the nearly 800 cities with populations over 100,000 people that were included in a WHO survey. The smoggiest were typically in the eastern Mediterranean and Southeast Asia, where air pollution in two-thirds of the cities measured saw increases in soot and small particle concentrations of 5 percent or more. The highest were dozens of times worse than the standards the UN agency recommends.

The WHO blames air pollution for more than 3 million premature deaths every year from ailments like lung and heart diseases. And as is commonly seen with other environmental issues, richer countries fared better than poorer ones.

"In general, developed countries have addressed air pollution in a way that is more consistent, and they have experienced improvement in air quality," said Dr. Agnes Soares, the regional advisor for environmental epidemiology at the Pan-American Health Organization, the WHO's regional affiliate for the Americas. "Although you still find many areas where this has not happened."

The study found 98 percent of the larger cities in low- or middle-income countries failed to meet WHO guidelines. But even in higher-income nations, 56 percent flunked. And in places like Mexico City, which has been working to clean up its notoriously chunky air, the results haven't been enough to hit the WHO's targets, Soares said.

The biggest problems tend to be in countries that still rely on stoves for cooking and lack reliable electric power, Soares said.

"In Haiti, for example, more than 90 percent of the population uses either charcoal or wood to cook," she said. "This is the highest contributor, but also the use of diesel for electricity is a big contributor." And in developing countries, meanwhile, increasing traffic and power plants that run on coal tend to run up pollution figures.

"Development per se is not bad, and industrialization can be good," she said. "But if we want to improve the health of the people, we have to think about how to control air pollution as well."

The WHO included the two most common pollutant readings — fine particulates, smaller than 2.5 micrometers, and coarser particles up to 10 micrometers, or about a tenth the width of a typical human hair. The agency recommends concentrations of those pollutants be no higher than 20 micrograms per cubic meter of air for PM10 and no more than 10 for PM2.5.

"PM2.5 in general is more toxic than PM10, but PM10 is not benign and can also cause problems," said Dr. David Peden, director of the University of North Carolina's Center for Environmental Medicine.

But cutting those pollutants can result in swift results, Peden said. When Atlanta restricted traffic around large parts of town for the 1996 summer Olympics, doctors recorded a decrease in asthma-related hospital emissions. The Chinese capital Beijing saw similar results when it tried to clear the air ahead of the 2008 games, he said.

"They basically shut down industries for a couple of weeks, and people could not drive their car but every other day," Peden said. "It was quite draconian in some ways for the individual. But that resulted in notably cleaner air during the Beijing Olympics, and as those restrictions were eased, the pollution returned."

Peden said there are less dramatic ways to reduce pollution — "But I think the ultimate solution for all this will largely be engineering."

"It will be developing and harnessing fuel sources that do not involve burning carbon to be able to generate electricity, heat water, and give us energy to do what we need to do on a daily basis," he said. "That's where ultimately a lot of the solution needs to happen. But in the meantime, being more efficient, and maybe burning less during certain times of the year when the air gets trapped, might be useful interventions."

And Soares said national leaders should think of pollution as a health problem, one that can drain budgets swiftly.

"This not only increases mortality — you have a decrease in life expectancy — but also it increases the number of people with disabilities, living many years under treatment," she said. "That is not only a heavy burden for the person, for the families, but also for the health system."

Two cities split the dubious honor of having the worst air in the world: Zabol, in southeastern Iran, had the highest PM2.5 concentrations, at an average of 170 per cubic meter. Onitsha, in southern Nigeria, edged out Zabol and the Pakistani city of Peshawar with a PM10 count of 594.

Beijing, which has become synonymous with smog since the country's rapid industrialization, ranked 59th-worst with a PM2.5 count of 85. Its PM 10 count of 108 was good for 156th place.

The cleanest air in the survey was in Sinclair, Wyoming, a town of about 420 people in the desert highlands between Cheyenne and Salt Lake City. Sinclair scored an average PM2.5 count of 2 and a PM10 count of 3.

Follow Matt Smith on Twitter: @mattsmithatl