Already athletes around the world with gold medal hopes are wondering if their stay in Beijing will permanently damage their respiratory systems. The intensely polluted Chinese city is aware of the concerns about its air quality, and is taking every step it can to reduce the problem before the Olympic Games kick off in August, including calling a halt to car repairs and spray painting.

Just yesterday, news broke that China had surpassed the United States as the world’s biggest polluter, a figure staked largely on the emissions of its enormous fleet of vehicles.

The study, conducted by the U.S.’s University of California, claims China’s pollution levels could have been the highest in the world as much as two years ago, but models that estimated China’s emissions were underestimating the country’s incredible growth rate.

China’s efforts to curb the output of its multi-million car populous in Beijing led the city to ban half the vehicles from the streets on alternate days, based on the last digit in the car’s license plate number. The plan started in August of last year and is expected to continue at least through the end of the Games.

The multi-tiered approach, which also includes cleaning up coal plants and smoking bans in stadiums and the like, is having a measurable effect. The number of days of cleaner air rose from 100 in 1998 to 246 last year, according to Beijing’s Environmental Protection Bureau.