To insure that data of PM25 and PM10 in the four cities are accurate and compatible , the QA / QC requirements of selection and weight of filters , the procedures of weighting filters were recommended .
为保证四城市PM25和PM10的监测数据准确，具有可比性，本研究规定了滤膜的选择、称量操作步骤的要求和滤膜称量的质控指标。
pm25