WHO: Iran, South Asia Ranked Worst in Urban Air Pollution

Air quality continues a downward slide worldwide, according to the World Health Organization

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Carlos Barria / Reuters

Tiny particles are floating in the air. You breathe them in every day. They enter your lungs and, if they’re small enough, they can go directly into your bloodstream. Not all of them are harmful, but like most substances, certain types can become hazardous at higher rates. They can cause heart disease, lung cancer, asthma and other life-threatening diseases and conditions. These tiny particles can kill, and in cities all over the world, the amount of them in the air is rising.

A new report from the World Health Organization looking at data from about 1,100 cities worldwide finds that average levels of particulate matter in the air are about 3 and a half times higher than WHO air quality standards. The report analyzes data on PM10 particles, particulate matter in the air that measures 10 micrometers or less. At this size, particles can easily enter the bloodstream. The WHO recommends an annual average of 20 micrograms per cubic meter as an acceptable level. The global average is 71 micrograms. The worst air quality was reported in Ahwaz, Iran, with reported average levels of 372 micrograms. Other cities at the bottom of the list include Lahore, Pakistan, Ludhiana, India and Ulaanbaatar, Mongolia, each with levels above 200 micrograms.

Commonly produced through fuel-combustion and industrial activity like power production, these particles are increasingly present in urbanized areas. The report finds that the vast majority of urban dwellers are exposed to levels of particulate matter that greatly exceed the WHO’s air quality standards. The Eastern Mediterranean, South East Asia, the Western Pacific and Sub-Saharan Africa all have levels that range from four to seven times the WHO’s 20 micrograms standard.

The data presented in the report was collected between 2003 and 2010, with the majority being collected in 2008 and 2009. The WHO attributes 1.34 million premature deaths in 2008 to urban outdoor air pollution, an increase from the 1.15 million in 2004. The increase is linked to increasing urban populations and urban air pollution. It’s also attributed to improved data reporting and collection methods.

While the regional data suggests that the incidence of harmful particulates is much higher in developing regions, data within regions shows a disproportionate impact on lower income countries. Low- and middle-income nations in the Americas, for instance, are exposed to an annual average of 49 micrograms of particulate matter. Higher income areas (the U.S., the Bahamas and Canada) measure at 21 micrograms. The difference is even more stark in the Western Pacific. Countries like China, Vietnam, and the Philippines are exposed to an average of 93 micrograms, while places like Australia, Japan and the Republic of Korea see about 32 micrograms. This interactive map shows that Mongolia, Botswana, and Pakistan have the highest rates of exposure, with averages at or above roughly 200 micrograms.

The data in this report offers a broad overview of the state of global air quality, and highlights what seems to be a trend of decreasing quality worldwide. And until that quality stops sliding down, the mortality figures are likely to keep rising.

About the Author

  • Nate Berg is a freelance reporter and a former staff writer for CityLab. He lives in Los Angeles.