China ? Beijing’s pollution levels dropped Wednesday to less than half of the previous day’s, the lowest reading since authorities began pulling cars off the road and shutting down factories to address athletes’ concerns about air quality ahead of the Olympic Games.

A cooling wind and some rain helped sweep away pollutants and gave Beijingers a respite from the sultry heat and humidity that had cloaked the city for days.

The polluted skies over the Olympic host city have been one of the biggest worries for Olympics organizers.

The concerns prompted officials to institute drastic measures earlier this month, included pulling half the city’s 3.3 million vehicles off the roads, halting most construction and closing some factories in the capital and surrounding provinces.