Four types of face masks including fabric, surgical and for-air-mask, particulate respirator masks were evaluated for PMs removal efficiency (RE). Masks are mounted on a Ф6-cm-PVC pipe and the air was pulled out the box by a fan with varying speed. PM2.5 and PM10 in filtered air and in the background were measured by Plantower PMS7003 light-scattering sensors. The removal efficiency was calculated by a ratio of the difference between PMs concentration in filtered air to the background air. Each mask was tested with the ambient air from 2 to 6 days. In four type of masks, removal of PMs of the fabric is 8.2%-14%, the surgical is 29%-39%, the air mask is 0.03% to 41% and 3M masks are 48-58%, AQBlue, Airphin masks are from 90-95%. Analysis of RE with airflow rate and photographs of the internal structure of the masks supports the RE result. A correlation of airflow to RE from -0.76 to -0.89 indicated a lower RE to a higher flow rate with surgical and air masks. The correlation coefficient of -0.51 for 3M Aura suggested improvements to airflow a higher airflow without significant RE reduction. Fabric masks, which are the dominant type on Hanoi streets, is not effective to filter out PMs. 3M-brand masks showed the highest removal but not high as 90%+ with standard tests. The form fitting is not evaluated in this study.