Following deaths and recent serious accidents to experienced and well known players, and to follow all the other equestrian disciplines, the HPA need to enforce the use of proper headgear to make polo safer. It is very fast contact sport and falls are commonplace. Recent research has shown that even mild brain injuries with no loss of consciousness can cause dementia and worse in later life. 
The HPA need to insist upon helmets that have been satisfactorily tested by either UK or American safety institutions and that have a three point harness. 
Link to the Lancet Neurology article HERE:

http://download.thelancet.com/pdfs/journals/laneur/PIIS1474442214701619.pdf?id=haaWsogLyl6Ue8tIjz0Cu

All other discplines insist upon safe headgear, from Dressage to Eventing to Racing. There have been no deaths by head injury in racing, flat or jump, for over 20 years. 

This rule will make the sport safer, improve its image, and help protect players from life changing brain injuries/death and the pain and suffering to loved ones that follows such incidents. "Sanity over Vanity"! #saferpolo

Photo with thanks to PoloLine and Matias Callego