Air Pollution Dangerously High in Hundreds of World Cities

air pollutionDirty air is a fact of life for most city dwellers around the world. Research on the true scale of urban air pollution problem is still necessary for policy reasons. A study by the World Health Organization (WHO), released on Thursday, shows that air pollution levels are dangerously high in hundreds of world cities.

The WHO collected PM2.5 particulate data from 1600 cities in 91 countries. PM2.5 is the diameter in microns of particulates of ammonia, carbon, nitrates, and sulfate that are small enough to pass into the bloodstream through the lungs and cause diseases, including cancer and emphysema.

The news isn’t good for people living in the 1600 cities that submitted data. Only 12 percent of the people living in those cities are breathing air that meets WHO guidelines. About 50 percent of the people are exposed to air pollution at least 2.5 times higher than what the WHO considers safe. Those people are at increased risk of long-term health problems because of that air pollution.

The survey found that air quality in most cities that monitor their air pollution is higher than the WHO considers safe. The WHO collected data on particulate matter, known as PM2.5 from the size of the particles. PM2.5 is considered the most dangerous to human health.

Half of the 20 dirtiest cities are India. Delhi, India came out the worst in the survey, with the highest level of particulate pollution with 153 micrograms per cubic meter of air. Patna, India was in second place with 149 micrograms. Both figures are approximately six times the 25 micrograms that the WHO considers a “safe” level of PM2.5 exposure.

India’s Center for Science and Environment, a public interest organization, cites weak enforcement of pollution control laws as one reason for Delhi’s air pollution.

Twenty-four of the 32 cleanest cities, with a PM2.5 reading of five or less, were in Canada, including Vancouver. Seven of the cleanest cities were in the United States. Hafnarfjordur, Iceland also made the list. Still, air pollution is dangerously high in hundreds of world cities, including cities in China.

No Chinese cities were in the top 20 list, in spite of the famous pollution issues in cities like Beijing. Beijing’s city government started publishing hourly PM2.5 numbers in January 2012. Beijing’s government reported a PM2.5 concentration of 89.5 micrograms in 2013, which is 156 percent higher than China’s standard. That reading would put Beijing in 17th place in the WHO report.

Maria Neira, Director for Public Health, Environmental and Social Determinants of Health at the WHO said that the study was meant as a “challenge” to cities. She thought the results would help cities become more open about air pollution, which comes from a combination of traffic, coal-burning power plants and heavy industries. Burning wood, dung, and charcoal for heat and cooking also contributes to urban air pollution in the world’s cities.

She did not think China might be cheating, saying that Chinese authorities were becoming better at collecting air pollution data.

This new WHO studies points to major air quality issues for most of the world’s city dwellers. The lack of data on China’s huge cities does not undermine the conclusion that particulate air pollution is dangerously high in hundreds of world cities

By Chester Davis

World Health Organization