The effect of particle size, meteorological parameters, and building airtightness on particulate matters infiltration

Introduction: The present study analyzed the infiltration behavior of size- fractionated particles and the influencing parameters. Materials and methods: The studies were carried out in two apartments under varying conditions of airtightness, utilizing real-time surveillance of Particulate Matters (PM0.3, PM1.0, PM2.5, PM10), along with air exchange rates and meteorological factors. The seasonal variations of the indoor dissemination of particulate matters have been also discussed. Results: The analysis of correlations indicated a strong dependency of indoor Particulate Matter (PM) concentrations on outdoor levels. However, the penetration patterns varied across different particle sizes. The highest contribution to outdoor PM10 was observed for PM 2.5-10 while indoors, the predominant particle size was among the finer categories, PM0.3-1.0. Moreover, window air-tightening appeared to decrease the overall effective leakage area of the building envelope, which in turn slightly lowered the ratio of indoor to outdoor PMs as well as the infiltrability for particles of all sizes. However, this intervention did not alter the distribution of particles within indoor environments.The most penetrated particles were observed in the size range 0.3-1.0 µm and then PM<0.3 µm, and the least in the size range 2.5-10 µm. Conclusion: Particle dimensions and external sources primarily influenced the degree of particle infiltration, significantly overshading the impact of weather-related factors. The relationship between indoor and outdoor particulate matter was diminished by the airtightness of windows, particularly for larger particles. No notable difference was observed in the infiltrability and indoor distribution of particles of varying sizes between the winter and fall seasons.