Police say they believe the blasts were deliberate but they haven't said who did it or why. Chinese authorities are not ruling out terrorism. There are now three rings of security cordons around Beijing, and stepped up security surveillance within the city. This cab driver says traffic has been much slower. Not everyone is very accepting about the heightened security measures. this tourist says he was checked for drugs at a recent party that was broken up by police. Police have started to crack down more on drug users, with a watch towards black customers in particular which is not good news for African or African-American Olympics competitors. The new regulations have cleared the air and thinned traffic on the roads. There have been four blue sky days in Beijing in the past month, which is normally a rare treat. That's because vehicles have to take turns on the roads, and many major plants have either reduced business or shut down for the month completely. Public transportation today was crowded today, but this company driver says he likes the changes so much he wouldn't mind the system continuing after the Olympics, and it would be worth it for cleaner air.