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You might have heard that birds are more susceptible to air pollution than humans. Here, we’ll break down how birds breathe, and how this adaptation makes birds more vulnerable to wildfire smoke and other air pollutants. Unlike humans, birds utilize unidirectional air flow that pushes air into the lungs during both inhalation and exhalation. This is made possible by a series of air sacs that connect to the lungs. During the first inhale, air enters the posterior air sacs behind the lungs. During exhalation, that same air exits the air sacs and enters the lungs, where gas exchange takes place. During the next inhale, the newly oxygen-depleted air exits the lungs and enters the anterior air sacs (those in front of the lungs); at the same time, fresh outside air is pulled into the posterior air sacs. With the next exhale, the stale air in the anterior air sacs exits the the body while the oxygen-rich air in the posterior air sacs enters the lung. Confused? Yeah, it’s pretty wild. Check out this video to learn more about how birds breathe. This system ensures that fresh, oxygen-rich air is constantly supplied to the lungs and never mixes with oxygen-depleted air, resulting in a higher concentration gradient of oxygen between the air in the lungs and the blood, thereby allowing more efficient gas exchange. TL;DR: Birds can take up about twice as much oxygen with each breath than we do. But, this highly efficient respiration is a double-edged sword. While birds are very good at supplying their bodies with oxygen, they are also more vulnerable to toxic air pollutants, such as those in wildfire smoke. Smoke contains high levels of fine particulate matter and noxious gases. On smoky days, birds’ exceptionally efficient respiration becomes a disadvantage. Smoke exposure contributes to a wide range of health effects in birds, including higher risk of infection, damage to lung tissue, and lung and heart disease.
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