The report includes: 1) a review of the scientific literature dealing with bioaerosols, filtration and how this influences the design and performance of FPE; 2) a review of the scientific literature of the organizational, environmental and individual factors that influence the effectiveness of occupational health and safety in general, and infection control procedures, in particular 3) an analysis [...] Added to the individual risk of the source patient were the risks associated with the hospital environment in terms of whether the patient wore a mask in hospital, was nursed in isolation and the state of the hospital ventilation system. [...] The drafts from each group were merged, then the compiled version reviewed by the team as a whole, and the summary of the evidence, the gaps in the evidence and the recommendations for further research were then determined with consensus from the research team. [...] Part A discusses the science of air-borne particles and the evolution of respirators and summarizes the advantages and disadvantages of respirators in the health care setting. [...] The effects of the high relative humidity in the respiratory tract can result in the relative size of particles increasing in aerodynamic diameter which, in turn, can affect the site of deposition in the respiratory tract [9].