Modelling Inhalation Exposure to HCFCs and HFCs in Residential Air Conditioning Using a Concentration – Exposure Duration (Log – Log) Approach

Hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs), widely used in air-conditioning systems, may be released into indoor environments through accidental leaks, resulting in potential inhalation exposure and associated health concerns.This study aimed to model human inhalation exposure under representative leakage conditions and derive corresponding experimental doses for Wistar rats to support toxicological assessment.Atmospheric concentrations were estimated using a Well-Mixed Room model under six leakage scenarios, and human inhaled doses were extrapolated to rats using allometric scaling.Uncertainty was quantified using Monte Carlo simulation with 10,000 iterations.Concentration-time relationships were evaluated using Pearson correlation and weighted least-squares (WLS) and generalized least-squares (GLS) regression models.The estimated inhaled doses for rats ranged from 41.3 to 110.1 mg/kg/day.The six leakage scenarios demonstrated very strong concentration-time correlations (r = 0.997-1.000;p < 0.01).The concentration-time relationship followed a generalized Haber relationship, expressed as log(C) = 4.919 -0.400 × log(t).Among the regression models evaluated, the GLS model provided the best fit (adjusted R² = 0.9981; p = 0.0182) and Modelling … DJOSSOU Vidémé Amèh et al.