Across the country, special fares were on offer in operation on public transport, exhibitions will show the effect of pollution on people and buildings, and new non-polluting types of transport will be on display.

BBC: News | Europe | Off the roads

"There's definitely a performance-enhancing effect if you use things that improve oxygen transport to the tissue, " says Larry Bowers, an expert on athletic drug testing and senior managing director of the U.S. Anti-Doping Agency.

FORBES: Magazine Article

The city's transportation agency, Transport for London, reported moderate traffic problems Wednesday morning as the rules went into effect.

CNN: First 2012 Olympics contests kick off