The ongoing effects of bush fires in NSW is threatening a race meeting in Sydney.

Friday's twilight racing at Randwick is in doubt because of poor air quality from the smoke surrounding the city.

Racing NSW said it had received advice from the NSW Department of the Environment that Friday's forecast air quality will be regarded as hazardous.

Stewards and veterinary officers will monitor conditions throughout the morning to decide whether the meeting will go ahead.

Several meetings in NSW have been lost in the past few weeks because of poor air quality and travel problems associated with bush fire areas.