# Development of a New Evaporation Exposure Model: Chemical Product Evaporation Model (CPEM)
## 4 Results
### Comparison between the CPEM and Simplified CPEMs
There were no significant differences between the models with and those without saturation kinetics. When the maximum values of \(K\) and \(S\) were used, the concentration of the target substance in the air was predicted to be higher than the minimum values of \(K\) and \(S\) because the amount of substance evaporated in air was proportional to these parameters. The ConsExpo evaporation model estimates of the concentration of the target substance in air were always smaller than those of the other models. In the ConsExpo evaporation model, only the target substance evaporates, so the substance concentration in the product always decreases. Therefore, when comparing the five models, the ConsExpo evaporation model estimated the lowest concentration of the target substance in the air. Figure 4 shows a comparison of the results obtained for the CPEM and ConsExpo models under three active ventilation scenarios. The differences in the concentrations of the target substance in the air continuously increased during the period of use. Even with active ventilation, in the CPEM, the concentration of the target substance in the air increased as the mass of the product decreased over time. The more frequently active ventilation was conducted, the more frequently the substance was removed from the air, and the average concentration decreased. It can be seen that the time-integrated average concentration of target substance in the air with active ventilation once a day (Figure 4b) is higher than with active ventilation twice a day (Figure 4c). Figure 4: Comparison of the target substance concentrations in the air under different ventilation conditions. The graphs on the left show the air concentrations of the target substance, and the graphs on the right show the time-averaged concentration of target substance in the air over 1 month. The simulation parameters are presented in Table 1. (**a**) No active ventilation, (**b**) active ventilation once a day, and (**c**) active ventilation twice a day. Comparison of the Use of Direct versus Indirect Methods to Estimate the Evaporated Amount of the Target Substance  
Here, we considered a case in which the target substance in a product evaporates completely before the exhaustion time of the product and another case in which the target substance does not evaporate completely before the exhaustion time. In Figure 5, \(M_{prod}^{c}\) was calculated assuming that \(M_{prod}(\Delta T)=0\), where \(\Delta T\) is the exhaustion time of the product. In other words, it was assumed that there would be no target substance remaining in the product at the product exhaustion time. If the target substance is completely evaporated by the exhaustion time, \(C_{air}^{ss}\) in Equation (18) is equal to the time-averaged concentration of the target substance in the air estimated by CPEM at product exhaustion time \(\Delta T\) (Figure 5a). However, \(C_{air}^{ss}\) is greater than the time-averaged concentration of a target substance in the air estimated by CPEM when the target substance in the product is not completely evaporated by the exhaustion time of the product (Figure 5b). In this case, the other materials evaporate faster than the target substance, and the target substance remains coagulated after the product is exhausted. Furthermore, it is expected that the average concentration of the target substance in the air can be estimated from the measurement of the remaining amount of the target substance in the product, which would be a useful screening tool (Equation (18)).