Infant and Adult Inhalation Exposure to Resuspended Biological Particulate Matter

Abstract

Human-induced resuspension of floor dust is a dynamic process that can serve as a major indoor source of biological particulate matter (bioPM). Inhalation exposure to the microbial and allergenic content of indoor dust is associated with adverse and protective health effects. This study evaluates infant and adult inhalation exposures and respiratory tract deposited dose rates of resuspended bioPM from carpets. Chamber experiments were conducted with a robotic crawling infant and an adult performing a walking sequence. Breathing zone (BZ) size distributions of resuspended fluorescent biological aerosol particles (FBAPs), a bioPM proxy, were monitored in real-time. FBAP exposures were highly transient during periods of locomotion. Both crawling and walking delivered a significant number of resuspended FBAPs to the BZ, with concentrations ranging from 0.5 to 2 cm (mass range: ∼50 to 600 μg/m). Infants and adults are primarily exposed to a unimodal FBAP size distribution between 2 and 6 μm, with infants receiving greater exposures to super-10 μm FBAPs. In just 1 min of crawling or walking, 10-10 resuspended FBAPs can deposit in the respiratory tract, with an infant receiving much of their respiratory tract deposited dose in their lower airways. Per kg body mass, an infant will receive a nearly four times greater respiratory tract deposited dose of resuspended FBAPs compared to an adult.

Motor Development: Embodied, Embedded, Enculturated, and Enabling

“…Through a surprising cascade of events, crawling may be linked to respiratory infections and asthma (Wu et al 2018). What is the link?…”

Building upon current knowledge and techniques of indoor microbiology to construct the next era of theory into microorganisms, health, and the built environment

“…Moisture is one of the most potent contributors to microbial survival in air and on surfaces [100][101][102][103], including resistance to electrostatic charges on surfaces [104], microbial activity [86,105], and the structure of the microbial community overall as survivors prosper [34,56,106]. The ability of microbial cells or spores to become aerosolized from surfaces and be resuspended into air due to occupant traffic or disturbance [107,108] is increased by a lowrelative humidity [109]. Low-relative humidity, such as 20-30%, increases the infection rates of aerosolized particles, such as influenza [110,111], as well as overall HAI frequencies [112].…”

Longitudinal development of the dust microbiome in a newly opened Norwegian kindergarten

“…Exposure to floor dust might potentially have a larger impact on children than adults as the former are in a more active developmental phase, particularly with regard to immune function. One study suggests that concentrations of resuspended floor dust bacteria can be as much as 9–21 times higher close to the floor in the infant breathing zone than further up in the adult breathing zone [ 27 , 28 ]. Characterization of floor dust might then provide useful information on exposure to environmental bacteria, especially when considering environments primarily inhabited by small children.…”