Airplane flights have increased in frequency and duration in recent years, as the world has become more interconnected. Along with this increase in air travel has come an increase in the amount of time that people spend exposed to recycled air. Some passengers may be concerned about the potential health effects of this exposure, but a new study suggests that there is no cause for alarm. Scientists have found that airplane cabin air is well-ventilated and there are low levels of air pollution on airplanes. It does not pose a significant health risk. The researchers measured the amount of carbon dioxide in the air on a variety of different flights and found that the levels were consistently low. In fact, they found that the average person would have to spend more than 24 hours in an aircraft to reach the same level of carbon dioxide exposure as they would experience in a single hour in a typical office or classroom. The results of this study should reassure travelers that, despite spending hours cooped up in a metal tube, they are not at risk of exposure to harmful levels of air pollution.