Agence France: International experts are warning that potentially lethal air pollution has boomed in fast-growing big cities in Asia and South America in recent decades. While Europe has managed to drastically cut some, but not all, of the most noxious pollutants over the past 20 years, emerging nations experienced the opposite trend with their fast economic growth, scientists at the UN’s meteorological agency said. Their comments came ahead of World Meteorological Day on Monday, which this …