A racing club on the NSW Far South Coast has banned cloth masks at an upcoming race to prevent the spread of the COVID-19 Delta strain, despite the masks still being accepted under NSW's public health order.

The Sapphire Coast Turf Club at Kalaru is hosting the Eden Cup Race Day on July 25 and has made it mandatory for patrons and essential personnel attending the event to wear an "N95 or surgical" face mask.

Club secretary Rob Tweedie said cloth masks would not be permitted at the event.

"A lot of masks are homemade and anyone can make them out of any material," he said.

Mr Tweedie said the club was following advice provided by Racing NSW, which states on its website that anyone attending a NSW race meeting must wear a specific mask.

'Mandatory face masks (N95 or surgical) are to be worn by all persons attending a NSW race meeting.

"N95 masks are the most effective mask to prevent the spread of the Delta strain and accordingly persons are requested to use this type of mask. At a minimum, a surgical mask must be worn.

"Cloth masks are ineffective against the Delta strain and therefore their use is not permitted."

In a statement, Racing NSW's chairman of stewards Marc Van Gestel said: "Racing NSW has engaged the services of a bio-security expert who has recommended the use of N95 or KN95 masks as the most effective in preventing the spread of the Delta strain of COVID-19."

Masks on

The NSW government has made face masks mandatory in some settings and stated cloth masks are acceptable if made and worn correctly.

ANU Medical School's Professor of Infectious Diseases Peter Collignon said surgical masks provided better protection than cloth masks, but that cloth masks were appropriate to use.

Professor Collignon said N95 masks could be difficult to breathe in and may possess expiratory valves.

"If you cough or splutter, all your bugs will go straight out of that valve," he said. 

"I think they (Racing NSW) have to be very careful recommending N95 masks unless they really specify you can not have an expiratory valve on it.

Easier on race day

Club secretary Rob Tweedie said staff were not in a position to check on race day if cloth masks worn by patrons were fit for purpose, which is why they were enforcing Racing NSW's advice.

"We can't be asking people to take their masks off and screening them to see how many layers they've got or how many filters. There's all sort of masks floating around," he said.

"That's the rules to get in the gate and that's what our security will be enforcing."