HONG KONG, August 8, 2008 (AFP) - The tropical storm that buffeted Hong Kong ahead of the Olympics this week has had one benefit, clearing the choking smog that frequently envelops the city.

Pollution levels in Sha Tin, where the first Olympic equestrian events will be held on Saturday, have fallen to low, the Hong Kong Observatory said Friday.

Hong Kong frequently suffers heavy pollution -- less than two weeks ago the Observatory put levels at 'high' and the city was blanketed in a haze that cut visibility to about three kilometres.

Organisers of the equestrian events said pollution was not a major problem as consistent rain was helping to clear the air.

However, they said the high levels of humidity could be a problem as it traps air pollution.

The territory is plagued by filth that blows in from the thousands of factories in China's industrial belt just over the border.

Hong Kong's hot and humid summer weather has been a contentious issue since the southern Chinese territory was designated an Olympic venue.

The events were re-located to Hong Kong so that the local Jockey Club, which controls the lucrative racing industry here, could bear the expense of building venues -- spending more than 100 million US dollars -- and because China could not guarantee a disease-free environment for the horses.

The Observatory is predicting temperatures of 30 degrees Celcius (86 Fahrenheit) and relative humidity of 95 percent for the coming week.