Defining air quality standards for pesticides through population exposure modeling

Atmospheric pesticide pollution is a global problem that poses risks to human health. However, controlling air pollution remains challenging, as few countries have established air quality standards (AQS) for pesticides. Here, we proposed a modeling framework based on human exposure assessment, comprising scenarios: screening, advanced, and aggregated. In addition, the AQSs of 13 selected pesticides in China were simulated using this framework as practice. In the screening scenario, the inhalation rates by age were included in the exposure assessment. The results showed that the adjusted exposure coefficients (θ_screening) were below 1 in young age groups, indicating that the derived AQS_screening should be stricter than the reference concentration (RfC) to ensure sufficient protection across all age groups. For the advanced scenario, outdoor and indoor conditions, as well as physical activity levels were incorporated into the exposure assessment. The results revealed that adjusted coefficients (θ_adv) exceeded 1 at all age groups, suggesting that a more lenient AQS could be appropriated for a pesticide in this scenario. For the aggregated scenario, exposure source allocation within the human body was considered in the exposure assessment to ensure a sufficient safety margin. The result found that the simulated adjusted coefficients (θ_adv) were generally two to four orders of magnitude below 1. This scenario could provide the most conservative simulated AQSs. In conclusion, the proposed framework can assist environmental agencies in comprehensively assessing human exposure and provide the potential adjusted coefficients for AQS derivation. Future research is recommended to refine the framework with more factors related to human exposure.