Prolonged inhalation of polluted air, especially fine PM2.5 particles, significantly reduces the health benefits of regular exercise, although exercise still helps to prolong life. The study, which spanned more than a decade and involved more than a million adults, showed that in areas with high concentrations of pollution, the protective effect of exercise on health is weakened. Thus, air pollution is quietly "erasing" the benefits of exercise, especially in regions exceeding the key PM2.5 limits that are common in several parts of the world. Scientists stress that exercising in the fresh air should not be discontinued, but improving air quality could bring much more significant health benefits. This study highlights the need to combine the promotion of physical activity with the reduction of air pollution for better population health. The results underscore that protection from the harmful effects of pollution is key to maximizing the positive health effects of exercise.