A smoggy day in London town? Mayor Ken Livingstone plans to change that: Beginning next year, motorists entering central London between 7 a.m. and 6:30 p.m. will have to pony up five pounds ($7) per day. About 40,000 vehicles per hour enter central London, a figure officials hope will drop by 15 percent thanks to the “congestion tax.” Critics say that before the tax is imposed, the city’s beleaguered public transportation system should be overhauled to accommodate the expected rise in users. Livingstone, meanwhile, said the program was necessary because some areas of the city had become “unlivable” due to pollution, congestion, and noise; moreover, traffic speed in the city currently averages just 9.9 mph. Singapore, Melbourne, and Oslo all have similar congestion taxes in place.