countries, the paramedic may take on the role as part of a system to prevent hospitalisation entirely and, through practitioners, are able to prescribe certain medications, or undertaking 'see and refer' visits, where the paramedic directly refers a patient to specialist services without taking them to hospital. Occupational hazards Paramedics are exposed to a variety of hazards such as lifting patients and equipment, treating those with infectious disease, handling hazardous substances, and transportation via ground or air vehicles. Employers can prevent occupational illness or injury by providing safe patient handling equipment, implementing a training program to educate paramedics on job hazards, and supplying PPE such as respirators, gloves, and isolation gowns when dealing with biological hazards. Infectious disease has become a major concern, in light of the COVID-19 pandemic. In response, the U.S. Centers for Disease Control and Prevention and other agencies and organizations have issued guidance regarding workplace hazard controls for COVID-19. Some specific recommendations include modified call queries, symptom screening, universal PPE use, hand hygiene, physical distancing, and stringent disinfection protocols. Research on ambulance ventilation systems found that aerosols often recirculate throughout the compartment, creating a health hazard for paramedics when transporting sick patients capable of airborne transmission. Unidirectional airflow design can better protect workers. History Early history Throughout the evolution of pre-hospitalization care, there has been an ongoing association with military conflict. One of the first indications of a formal process for managing injured people dates from the Imperial Legions of Rome, where aging Centurions, no longer able to fight, were given the task of organizing the removal of the wounded from the battlefield and providing some form of care. Such individuals, although not physicians, were probably among the world's earliest surgeons by default, being required to suture wounds and complete amputations. A similar situation existed in the Crusades, with the Knights Hospitaller of the Order of St. John of Jerusalem filling a similar function; this organisation continued, and evolved into what is now known throughout the Commonwealth of Nations as the St. John Ambulance and as the Order of Malta Ambulance Corps in the Republic of Ireland and various countries. Early ambulance services While civilian communities had organized ways to deal with prehospitalisation care and transportation of the sick and dying as far back as the bubonic plague in London between 1598 and 1665, such arrangements were typically ad hoc and temporary. In time, however, these