Study on particle penetration through straight, L, Z and wedge-shaped cracks in buildings

Blower-door estimates of PM2.5 deposition rates and penetration factors in an idealized room

“…Chen and Zhao 11 found that increasing pressure differences, crack lengths and the roughness of the inner surface of cracks cause higher penetration factors. A negative relationship between the number of cracks right-angles and penetration factors was observed by Li et al 12 Particle deposition rate depends on factors including surface material, roughness of the wall, air-flow characteristics, etc. 13 Lai and Nazaroff 14 produced a mathematical model to predict particle deposition onto smooth surfaces as a function of particle size and density, while further work investigated the deposition of fine particles on vertical textile surfaces and examined different temperature gradients and air relative humidity (RH).…”

A Review of Recent Advances in Research on PM2.5 in China

“…Some scholars in China have also conducted researches on determining the penetration coefficient. Their studies mainly focus on some influencing factors that affect the penetration coefficient of fine particles, such as the height of the crack [ 190 ], the roughness of the inner surface of the crack [ 191 , 192 ], the indoor/outdoor pressure difference [ 192 ], crack geometry [ 193 ], ACH [ 194 ] and so on. Due to the limitations of available devices and testing conditions, only a small number of studies in China currently focus on studying the penetration coefficient of PM 2.5 alone.…”

Using Crowd-Sourced Data to Assess the Temporal and Spatial Relationship between Indoor and Outdoor Particulate Matter

“…Particulate matter (PM) is the largest environmental cause of mortality around the globe, with fine particulate matterparticles with a diameter less than 2.5 μmestimated to cause millions of premature deaths annually. , Although PM is produced by a vast array of sources, most of the dominant contributors, especially in regions that do not depend on biomass for cooking and heating, tend to be outdoors (e.g., transportation, electric power generation, industry, forest fires, dust). While the built environment provides shelter from the elements, it is an incomplete filter; PM can penetrate buildings through open doors and windows, and localized studies have shown that smaller particles can enter through the small cracks and porous materials that comprise the outer shells of nearly all structures. , Given that Americans spend approximately 85–90% of their time indoors, with the vast majority in a private residence, , any effort to understand and limit damages from PM will fundamentally hinge on the degree to which outdoor air pollution penetrates indoors.…”

“…While the built environment provides shelter from the elements, it is an incomplete filter; PM can penetrate buildings through open doors and windows, and localized studies have shown that smaller particles can enter through the small cracks and porous materials that comprise the outer shells of nearly all structures. 3,4 Given that Americans spend approximately 85− 90% of their time indoors, with the vast majority in a private residence, 5,6 any effort to understand and limit damages from PM will fundamentally hinge on the degree to which outdoor air pollution penetrates indoors.…”