A systematic review of 2,168 studies that looked into the adverse effects of wearing masks during the COVID-19 pandemic has found that the practice led to negative health consequences, including itching, headaches, and restriction of oxygen. “We found significant effects in both medical surgical and N95 masks, with a greater impact of the second,” states the review, published in the “Frontiers in Public Health” on April 5. A meta-analysis of multiple studies found that headache was the “most frequent symptom” among mask wearers, with a prevalence of 62 percent for general mask use and up to 70 percent when using...