Changes

| 19th century || || "The design of the mask took a big step forward in the 19th century. "<ref name="globaltimes.cn"/> "Throughout the 19th century, doctors continued to go without masks while workers in factories were encouraged to use them to help filter particle-ridden air."<ref name="gizmodo.coms">{{cite web |title=A Brief History of Medical Face Masks |url=https://gizmodo.com/a-brief-history-of-medical-face-masks-1843698852 |website=gizmodo.com |accessdate=11 September 2020}}</ref> "The practice of using face masks to prevent infection in hospitals started in the late 19th century."<ref name="bloomberg.comss"/> "in the 1800s there was an understanding of the usefulness of face masks in factories."<ref name="gizmodo.coms"/> "The modern surgical face mask came into use in the late nineteenth century, around the time that germs and viruses were reshaping medical understandings of disease."<ref name="We share what we exhale"/> " it was in the latter half of the 19th century – when medical research was benefiting considerably from Louis Pasteur’s work – that face masks began to be worn in hospital settings."<ref name="newseye.euv"/> "According to “History of Surgical Face Masks: The myths, the masks, and the men and women behind them,” by John L. Spooner, face masks first appeared at the very end of 19th century, used as a protective measure worn by doctors during surgery to prevent airborne bacteria from entering an open wound."<ref name="The Mask">{{cite web |title=The Mask |url=https://www.nytimes.com/2020/03/17/style/face-mask-coronavirus.html |website=nytimes.comwwww |accessdate=12 September 2020}}</ref> " In the mid-1800s, German scientists conducted studies with industrial dust and bacteria and their relationship with respiratory health"<ref name="cdc.govi"/>

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| 1870s || || "By the late 1870s, scientists learned about bacteria. Miasma fell from fashion as the modern field of microbiology emerged."<ref name="fastcompany.comsssa"/>