Assessment of Air Purification Effect in Sheltering Houses Equipped with Ventilation Systems after Air Pollution Incidents

A key issue in the later stage of an environmental emergency is indoor air purification. This study investigates a reasonable ventilation strategy for indoor air purification in the later stage of an air pollution accident. Using a closed test chamber to simulate a sheltering house with a ventilation system, the deposition rates of aerosol particles were measured under both ideal and non-ideal conditions. Additionally, the actual turbulence state can be inferred by querying the optimal K-e in the beta-K-e, diagram proposed by this work. The main removal mechanism for particles within the range of 53.3-371.8 nm at an air exchange rate less than 1.19 h(-1) is deposition. A ventilation system based on a high-power exhaust pump causes a large turbulence, which results in the resuspension of particles outside the cumulative mode range with a 'sudden drop' in the deposition rate. In the later stage of an air pollution accident or in the case where outdoor particles do not contribute indoors, turning off other stirrers and fans and increasing the AER value of the ventilation system to more than 1.19 h(-1) can achieve the desired air purification effect. However, particle removal in the cumulative mode remains a challenge.