The Environmental Protection Agency (EPA) started to establish a network of air quality monitoring stations in 1981, and it has undergone three major changes since then. According to the "102-109 New Generation Environmental Quality Monitoring and Testing Program" approved by the Executive Yuan, several works had been completed by 2020, such as checks and adjustments of air quality monitoring stations and update of equipment.
The key pollutants related to AQI in Taiwan are PM2.5 and ozone. Therefore, reducing the monitoring errors of PM2.5 and ozone is one of the important technical development tasks of the EPA. Set up in Fengshan District, Kaohsiung City, the Quality Assurance Laboratory, which belongs to the air quality monitoring station network, maintains relevant calibration techniques and measurement capacity. Therefore, it provides important functions to ensure the measurement accuracy of the instruments used, including flowmeters for PM sampling and ozone analyzers for ambient monitoring.
In the above-mentioned New-Generation program, the Department of Environ-mental Monitoring and Information Management in EPA started the replacement and update of automatic particulate monitoring equipment and utilized the newly set up comparison platform to incorporate equivalence comparison of manual and automatic equipment into the acceptance process of actual monitoring data. After the new instruments are officially put into operation, the comparison platform will be used simultaneously to conduct maintenance and precision testing of the automatic monitoring and inspection machines. A feasible mechanism is being developed for using automatic monitoring equipment to perform inspection operations under adequate quality assurance conditions.
Using the resources mentioned above, the objectives of this project include:
(1) Promote the performance evaluation of PM10 and PM2.5 automatic monitoring instruments; (2) Maintain the field comparison platform and parallel comparison check of PM10 and PM2.5 automatic monitoring instruments for the national monitoring network to ensure the performance of the instruments; (3) Maintain the calibration standard system and traceability of instrument flow for quality assurance.
Within the duration of the project, the comparison of data acquired by the PM2.5 automatic instrument and the standard method (manual) was conducted for the past two years. The results showed that the differences between the two could be effectively reduced by taking the enhanced maintenance measures implemented in 2011: (1) HEPA zero-point testing ＆ adjustment, and (2) heater off power adjustment. The performance of PM2.5 and PM10 automatic monitors was evaluated on a weekly and monthly basis. The monitors with significant deviations in monitoring values could be traced, and the maintenance personnel was requested to deal with them immediately. At the same time, a list of priority sites for QC checking was proposed based on the observed trend. For PM2.5, a total of 66 out of 60 station inspections committed in this project had been completed by Ocyober 2022. In summertime, the inspection work of QC checking was suspended due to the low environmental concentration. For PM10, a total of 45 out of 45 station inspections committed in this project had been completed by October 26, 2022. For the maintenance of the calibration system in Quality Assurance Laboratory of the air quality monitoring network, the focus of this year is to apply for ISO/IEC 17025 accreditation for the calibration system of the ozone automatic analyzer to ensure the international equivalence and metrological traceability of the calibration results. The assessment was already completed by the assessors appointed by Taiwan Accreditation Foundation on October 7, 2022.