Study of Environmental Particle Levels, Its Effects on Lung Deposition and Relationship With Human Behaviour

Abstract

The adverse impact of particulate matter (PM) on human health can be best explained in terms of PM deposition inside respiratory organs rather than the typically reported ambient exposure concentration. This study measured the PM mass concentration (MC) at various microenvironments inside a residential campus and estimated the corresponding PM mass deposition in human respiratory regions such as Head (H), tracheobronchial (TB) and pulmonary (P) organs. This was done using the Multiple Path Particle Dosimetry lung model. Particle size fractions in the range of 0.25–10 μm were measured by an optical particle counter during winter when the PM MC is significantly high. The results showed that MC varied widely at different microenvironments ranging from 169.7 to 604.9 μg/m3 for PM1 and 31.2 to 649 μg/m3 for PM10−1. The highest and lowest MC for both fine and coarse sizes were found in the canteen and library, respectively. Our model revealed that the total deposited fraction increased with higher physical activity (e.g. higher breathing rate). The deposition fraction increased consistently in the Head with increase in particle size for all physical activity levels, whereas it varied in the P region. Results for 24 h lung dosimetry computed for students displayed that the dose deposition for coarse size particles for all type of activities followed the same trend: H > P > TB. A similar trend was found for fine particles except during sleep and sit activity levels with dissimilar trend: P > H > TB. The total deposited dose was found highest at play court while lowest at canteen. This type of focused preliminary study is much needed as physical activity levels and time spent at particular microenvironment besides the PM exposure concentration and helps to determine the critical microenvironments.