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15 godz. temu · The second cleanest city is Perth, with 1.7 μg / m 3 and PM 2.5 levels dropping by -6.2 μg / m 3 since 2019. Of the top ten cleanest cities, five are from Australia. They are Hobart, Wollongong, Launceston, Sydney and Perth. Honolulu is the only U.S. city in the top ten list, ranking tenth with levels of 4 μg / m 3, with a tiny increase ...
