Respiratory protection strategies for the public in emergency response.

A strategy was established to minimize the stochastic effects of internal and external exposure to radioactive substances by wearing respiratory protection equipment (RPE) during an emergency evacuation. During the evacuation of residents in the event of a nuclear power plant accident, the stochastic effects of internal exposure caused by the inhalation of radioactive aerosol and external exposure due to accumulated radioactive particles in the filter medium of a mask must be minimized. The radioactivity concentration along an evacuation route considers atmospheric dispersion and the resuspension of particles deposited on surfaces. The effective dose due to internal exposure is evaluated using inhalation dose coefficients for each particle diameter. When the face seal leakage and filter medium penetration ratio for each particle diameter of the RPE (N95) is taken into consideration, the internal dose is reduced by 97.2%. Furthermore, the accumulated radioactivity in the filter medium decreases by 91.4% when the respirator is replaced every 48 h.