Simulation of particle transmission in an emergency waiting hall and management proposals

Abstract

Background: Particle transmission is relevant to nosocomial infection of respiratory infectious disease. It is essential to understand the particle concentration and movement and effect of respiratory protection in hospital to improve management proposals. Methods: The particle number concentration, air condition wind velocity and temperature were collected from 6 locations in an emergency waiting hall. The particle concentration in waiting area and consulting room and coughing exhaled particle transmission were calculated by Lattice Boltzmann Method, Convection-Diffusion Equation and Discrete Phase Model, respectively. Fit tests of 4 respirators among 577 health care workers in the hospital were carried out. Results: The wind velocity of air conditioner outlet was correlated negatively with particle concentration of diameter no more than 1μm(r=-0.671,P=0.000), either more than 1μm(r=-0.261,P=0.000). The particle concentration in the waiting area was higher than that in the consulting room both by field measurement and simulation. Particles exhaled by someone coughing can spread to several people around him or her within 1s. 60% of exhaled particles suspend for a few minutes or longer. The passing rates were 50%, 93.3%, 80.3% and 5.9% for 3M 9132, Siwo D918(hook), Siwo D918(headband) and Wenjian medical N95 respirator, respectively. The difference was significant in the same population(χ2=163.433, p=0.000). Conclusion: Protective strategies should be strengthened in the waiting area during respiratory infectious disease epidemic. Fit test is essential to health care workers to select respirators.