Deposition Of Size Distributed Atmospheric Aerosol In Human Respiratory System In An Urban Atmosphere

Abstract

Several epidemiological studies have reported the association of atmospheric particulate matter (PM_2.5) with daily and cardiovascular mortality specifically during wintertime and a higher risk of acute cardiovascular diseases, with systemic oxidative stress induced by air pollution as a potential underlying mechanism. The risk that the inhaled particles pose depends on their chemical composition and where they deposit in the respiratory system. Therefore, to adequately assess the health risks of aerosols, it is vital to understand the deposition of particles in the lungs. The efficient inhalation of pharmaceutical aerosols also depends on this kind of comprehension. This project attempts to understand the size distributed deposition in three major regions of the respiratory system. The multi-modal nature of urban aerosol mass distribution for Bhopal using log-normal distribution curves and the empirical equations using the International Commission on Radiological Protection (ICRP) model are utilized to estimate the regional and total deposition in the human lungs. The annual averages indicated a total deposition of 42 µg m^-3 with highest values observed during the summer month of April and lowest during September. Even though the overall deposition in the month of April is the highest (124.61 µg m^-3), most of the deposition in the month of April is in the head airways region (137.7 µg m^-3) which is protected by a mucociliary layer while the deposition in the alveolar region is low (4.43 µg m^-3). Generally, the deposition in head airways region is the highest followed by alveolar region. The amount of deposition in alveolar region dominates over deposition in other regions in the winter season (December, January, February) implying higher risk to lung capacity during these months.