(32cs) Activity-Based Inhalation Model for Assessing Occupational Exposure and Daily Intake in Industrial Environments

Inhalation exposure to airborne contaminants, including particulate matter (PM), dust, and other air pollutants, poses significant health risks, particularly in environments where contaminant concentrations fluctuate, such as chemical plants and refineries, i.e. occupational exposure. Traditional single-zone models often assume uniform distribution, potentially oversimplifying actual exposure dynamics. In the present work a refined two-zone inhalation model that accounts for spatial variability in chemical contaminants, PMs and dust concentrations across distinct environmental zones, enhancing precision in exposure assessment is introduced.

The primary objective was to develop and validate a two-zone inhalation model that quantitatively estimates inhaled doses of a chemical in the air as well as the amounts absorbed in PM and dust. This is crucial for accurately assessing human exposure because it enhances robust and reliable health risk assessments by capturing multiple exposure pathways, which supports more targeted safety guidelines and effective pollution control. The model distinguishes between high-concentration “near-field” and lower-concentration “far-field” zones, aiming to improve risk assessment accuracy for scenarios with spatially heterogeneous pollutant distributions. The model framework divides the exposure space into two zones based on the proximity to emission sources. Concentration data given the emission source are employed to characterize exposure levels within each zone. Thermodynamic characteristics of each chemical are also considered in this stage especially in the indoor environments. A set of differential equation systems models the transport and accumulation of particles within each zone, accounting for air exchange rates, deposition, and re-suspension processes. Inputs include measured concentrations of a specific chemical in the air, PM and dust particles, ventilation rates, and occupancy patterns. Inhalation exposure calculations integrate zone-specific concentrations with inhalation rates to estimate dose over time. Inhalation rates are derived from the work of Sarigiannis et al. (2012) and relied on the intensity of an activity that an individual performs.

Preliminary findings indicate that the two-zone model provides significantly different dose estimates compared to traditional single-zone models. In scenarios with high emission sources, the near-field zone exhibited concentration levels up to 2.5 times greater than far-field estimates. Model validation against experimental data demonstrated that this approach offers enhanced accuracy in predicting inhaled intake doses, especially under varying ventilation conditions and dust accumulation levels. These results underscore the importance of spatial resolution in exposure models to accurately assess health risks especially in industrial settings. The proposed two-zone model improves inhalation exposure assessment by incorporating personally resolved chemical concentrations. The model can also use sensor-sourced data allowing for robust personal intake assessments for the workers that face higher exposure risks. This advancement allows for more realistic risk assessments in occupational and environmental health contexts, particularly in settings where exposure levels vary significantly across zones, e.g., refineries. Future applications may extend to real-time modeling of indoor and outdoor air quality, supporting strategies for exposure mitigation and health risk reduction as well as the integration with fluid dynamics applications.

Sarigiannis, D., Karakitsios, S., Antonakopoulou, M., & Gotti, A. (2012). Exposure analysis of accidental release of mercury from compact fluorescent lamps (CFLs). Science of the Total Environment, 435–436(0), 306-315. https://doi.org/10.1016/j.scitotenv.2012.07.026