Does wearing a mask reduce oxygen?
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Wearing a mask does not significantly reduce oxygen levels, but it can increase carbon dioxide (CO2) levels slightly. According to , discomfort felt when wearing a mask is often due to the increased CO2 rather than a lack of oxygen. He emphasizes using a pulse oximeter, which shows that blood oxygen levels remain stable, even with a mask on 1 2.
However, specific types of masks, such as N95s, can impact breathing more severely. For instance, a controlled clinical trial found that wearing N95 masks reduced the volume of inhaled and exhaled air as well as overall oxygen consumption, particularly among pregnant healthcare workers 3 4.
In contrast, for general mask usage, the main impact is an increase in CO2, which can actually provide health benefits if oxygen levels remain adequate 5 1.
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