Facebook fact checks conservative page after it posted the side effects of mask-wearing found in Stanford study: Freedom in America shared a screenshot of a Stanford study which listed the physiological and psychological effects of mask-wearing. Facebook labeled the post "partly false" because scientists dispute one of the 32 listed side effects. The fact check links to a Lead Stories article written in response to a completely different post. While the Stanford study observed an increased risk of hypercapnia (excessive carbon dioxide levels in the blood), Lead Stories cites several studies showing mask-wearing generally does not cause hypercapnia. Posts that have been fact-checked lose exposure on Facebook feeds and ads as they are negatively affected by the platform's algorithm. According to Facebook, users fail to click through a fact-check interstitial to see the post 95% of the time.