A blueprint for well-designed, high-performing cloth masks that can outperform a 3-layered surgical mask

Introduction: During COVID-19, due to the worldwide shortages of medical masks, homemade cloth masks became a mainstay of the pandemic. The CDC and WHO recommend the use of homemade cloth masks. However, there is insufficient evidence on the performance: respiratory droplet blocking ability, water-resistant capacity, breathability, and washability of commonly used fabrics to design high-performing cloth masks that can outperform medical masks. Material and Methods: We conducted a series of experiments on aerosol blocking (using healthy volunteers sneeze, image-based flow measurement technique), water-resistant, breathability, and washability to evaluate all dimensions of protection of 17 different commonly available fabrics and their layered combinations. Results: The research provides a blueprint for the optimal design of a high-performing cloth mask that can outperform a 3-layered surgical mask. A minimum of 3 layers is recommended to provide the performance of surgical masks. A combination of cotton/linen for the inner layer, blends for the middle–layer, and polyester/nylon for the outer–layer. The average thread count (threads contained in one square inch) should be greater than 200, and the porosity (percent of pores in a fabric) should be less than 2 %. Increasing the number of layers increases the droplet blocking efficiency by approximately 20 times per additional fabric layer. Machine washing at 60 °C did not affect the performance of cloth masks. Conclusions: These results and visualizations can assist people in preparing effective homemade cloth masks during the ongoing COVID-19 pandemic and future epidemics.