“New Delhi has succeeded in arresting the trend, which shows that if you take action, you will see results,” said Anumita Roychowdhury of the Delhi-based Center for Science and Environment.
But India overall is still struggling. The WHO data showed four other Indian cities — Gwalior, Allahabad, Patna and Raipur — surpassing New Delhi to rank within the world’s top ten polluted cities — coming in second, third, sixth and seventh, respectively.
In Europe, the Bosnian city of Tuzla had the worst air on the continent, although its pollution level was far less than in much larger cities in India, Pakistan and China. The worst air pollution in a U.S. city was in California’s Visalia-Porterville area, but it too ranked far lower — 1,080th — than many developing-world cities.
Paris came in at 1116th most polluted, London at 1,389th and the New York-Northern New Jersey-Long Island region at 2,369th.
The database’s cleanest town was Sinclair, Wyoming, ranking 2,973th with a particulate matter (PM 2.5) of 3, compared to 217 for the most polluted city, Zabol.
WHO guidelines urge a PM 2.5 rating of 10 or less. But WHO technical officer Sophie Gumy cautioned against drawing too many comparisons between cities from different continents, saying the data from various sources doesn’t always line up exactly.
Some countries publish official air pollution statistics, but others don’t. Some of WHO’s data comes from academia. Some monitoring stations could be near highways, which could skew the results. Some data includes night air pollution, which tends to be less than during rush hour, but other national reports do not. And rainy seasons can rinse away air pollution, while drier climates can let the pollution linger.
The agency praised efforts by policymakers to promote cleaner transportation, more efficient energy sources and better waste management.
“More than half of the monitored cities in high-income countries and more than one-third in low- and middle-income countries reduced their air pollution levels by more than 5 percent in five years,” the agency said.
Source: www.manufacturing.net
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