A disease long associated with aging smokers may in fact begin its quiet work in the lungs of infants, shaped by the invisible air they breathe in their earliest years. Researchers in Basel have found that children carrying genetic markers for COPD show measurably slower lung growth by age six — but only when raised in environments with elevated air pollution, suggesting that the trajectory toward chronic disease is not written by genes alone, but by the world those genes inhabit. The finding asks us to reconsider where prevention truly begins: not in the clinic of a sixty-year-old, but in the