Final answer:
Asbestos is a powdery mineral that poses a health hazard when airborne, primarily causing lung cancer.
Step-by-step explanation:
The powdery mineral that is a health hazard when airborne is asbestos. Asbestos is a hazardous compound that was formerly used in many settings and its accumulation in well-insulated, tightly sealed buildings constitutes a health hazard, primarily lung cancer. When the paint containing asbestos peels and cracks, it releases asbestos dust which can be inhaled and cause serious health issues.