Ekpreechakul, MD, MSc T, Saiphiroonthong, MD, MSc W, Chaiwong,BSc, MPH W. Letter to Editor: Quantitative Fit Test of Double Layer Surgical Masks . BKK Med J [internet]. 2021 Feb. 27 [cited 2026 Oct. 3];17(1):70. available from: https://he02.tci-thaijo.org/index.php/bkkmedj/article/view/249330