Incense smoke (IS) inhalation exposure system: Physicochemical characterization, IS particle deposition and clearance in human airway using MPPD model

Incense smoke (IS) is source of indoor air pollution and key risk for diverse human diseases. Less information is available regarding controlled IS rodent inhalation exposure system and IS particulate matter (PM) deposition in human airways. Study aimed to demonstrate stable ISPM physicochemical parameters of 10 incense products inside the customized whole body inhalation exposure chamber (without animal) connected to smoke generation unit via aerosol mixing device. IS analyzed for size segregated PM emission, ISPM in vitro aerodynamics (MMAD and GSD determination), fine and ultrafine particle's SEM, SEM-EDX and PAH analysis. Using real life exposure scenario by utilizing MMAD, GSD and PM concentration after Tier 1 exposure assessment as key input parameters, ISPM dosimetry in infant (3 months) and adult (21 years male and female) human airways was calculated using multiple-path particle dosimetry (MPPD 3.04) modeling. Mass median aerodynamic diameter (MMAD) and geometric standard deviation (GSD) ranged between 0.55 and 2.10 mu m and 1.22 to 1.77 (polydisperse) respectively. PM1.0 and PM0.1 showed multiple morphology and presence of heavy and trace elements. PAH like acenaphthylene, anthracene, fluorene, naphthalene and phenanthrene were detected (0.84-143.17 mu g/g). MPPD results showed higher ISPM deposition in pulmonary region and lowest in trachea bronchial region. ISPM deposition in tissue was higher in lower, peripheral lung as compared to upper and central lung tissue. Whole body inhalation exposure system showed stable IS atmosphere (physi-cochemical parameters) indicating the device suitability in future inhalation studies. MPPD ISPM deposition fraction and clearance data showed deep lung penetrating and retention behavior with higher risk in infant followed by female and then male. These modeled particle deposition and clearance data may be useful in risk assessment analysis of IS.(c) 2023 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Automated summary

This study focused on the controlled inhalation exposure to incense smoke and analyzed the physicochemical parameters of the smoke particles. The results showed that the particles from incense smoke have a higher deposition in the pulmonary region and pose a greater risk to infants.