The goals of this study are (1) to maintain acid deposition network for conducting a long-term monitoring and data analysis, (2) to maintain the integrated atmospheric mercury monitoring network and analyze the data, (3) to evaluate the contribution of local and long-range transport air pollutants to acid deposition through classification statistics of weather patterns during rainfall and simulation results from an integrated atmospheric modeling system, (4) to evaluate the possibility of integrating the resources of both EPA and CWB by comparing the acid rain of both parties, (5) to assist EPA in integrating the acid rain website and compiling the acid rain annual report, (7) to promote international cooperation and technical exchanges on regional air pollutant transport issues. To date, our achievements are highlighted below: 1. The annual average pH for all the samples in 2021 and 2022 (Jan-Aug) were 5.92 and 5.80 separately. The acid rain situation in Taiwan has slightly improved. The annual average pH values for most of the sites are greater than 5.0. Annual average pH values at Northern Taiwan sites are still lower than in southern Taiwan. 2. From 2021 January to 2022 August, the total mercury concentration from each station was between 1.5– 141.1 ng L-1. The weighted mean mercury concentration was between 5.7 – 16.8 ng L-1. This range of mercury concentration in Taiwan is now lower than the most majority of countries worldwide. 3. We have integrated the content of acid rain website into Air Quality Protection Web (https://air.epa.gov.tw/) and compiled the 2021 acid rain annual report. 4. Continued to promote and participated in international collaborations and technical exchanges, for example with the Quality Assurance Science Activity Center of the UN, and the WMO Global Precipitation Chemistry and Deposition Science Assessment.

acid rain, atmospheric mercury, long-range transport