Aspergillus niger forms dry, powdery, jet-black colonies due to its dark spores. It is widespread in soil and on decaying plant debris, making its way into homes via airborne spores. In indoor settings, it commonly colonises damp bathrooms, leaking walls, or basements. While often considered a minor allergen, it can provoke respiratory issues in sensitive individuals. In rare cases, especially in immunocompromised people, it may lead to more serious infections such as aspergillosis.
