Why Mold Exposure Matters for Respiratory Health The idea of mold affecting the lungs can sound alarming — and for good reason. The respiratory system is especially sensitive to environmental irritants, including mold spores that circulate in indoor air. When we breathe, airborne particles enter through the nose and mouth. While the body has natural defenses like nasal hairs and mucus, some particles — including mold spores — can still reach the lungs. For certain individuals