APEX: A Web-Based Tool for Assessing Long-Term Outdoor PM Exposure-Brief Report.

Long-term exposure to ambient fine particulate matter air pollution (PM) is a major risk factor for lung cancer and other chronic diseases. However, assigning individualized long-term exposure estimates, both at the point of care and in epidemiologic research, remains a methodological challenge due to limited tools for integrating residential history with air pollution data. As a result, most studies estimate exposure based only on a participant's last recorded address. Here, we describe and demonstrate the use of the Air Pollution EXposure (APEX) tool, a web-based application that provides individual annual estimates for PM exposure from 1998 to 2024 based on a user-provided residential history. APEX can collect address histories through a user-friendly web interface to collect worldwide addresses with autocompletion and interactive map facilitating recall of partial addresses. Addresses are geocoded and linked to annual surface-level PM estimates. APEX also supports both single-entry and batch-processing entry modes for integration in clinical and research workflows. APEX outputs annual PM exposure values, geocoded address logs, and graphical summaries. APEX-derived exposure estimates have been used to support an epidemiologic analysis evaluating the association between PM and lung cancer risk. APEX enables scalable, reproducible, and clinically applicable PM exposure assessment, facilitating personalized evaluation for risk assessment and epidemiologic research for lung cancer, cardiovascular disease, and other conditions associated with air pollution.