When racing resumed behind closed doors in June, face coverings were made compulsory only in certain areas of the track, notably the parade ring.
But from next week they must be worn in all indoor and outdoor areas of the zones for both key personnel and for owners throughout the day, other than by those who need higher personal protective equipment, such as medical and cleaning staff.
Explaining the move BHA Chief Medical Adviser Dr Jerry Hill, said: "Even in the period since resumption, there has been a growing scientific consensus that, when used correctly, face coverings can help to reduce the spread of coronavirus droplets.
"With cases rising across the country and more areas subject to local lockdowns and restrictions, we believe that making face coverings compulsory for all – except, of course, where exemptions apply – is a sensible and necessary precaution."
Jockeys will still be allowed to pull down their face covering in the moments immediately prior to the start of a race and for its duration. But if the covering is lowered, it must now be raised again on completion before entering the horse walk.
Broadcast media need not wear face coverings when broadcasting live to camera or during live or pre-recorded interviews, although strict social distancing must be maintained at those times.
Other exceptions to the rule include clerks of the scales when appropriate risk mitigation is in place, starters immediately prior to a race and stewards while talking during an inquiry.
Those exempt from wearing a face covering due to physical or mental health reasons or disability may be required to provide verification from a healthcare professional.
The BHA now recommends masks and face coverings without valves as they offer superior protection to those in the area around the wearer.