Safety is the state of being "safe" (from French sauf), the condition of being protected from harm or other non-desirable outcomes. Safety can also refer to the control of recognized hazards in order to achieve an acceptable level of risk.
Metals released into the atmosphere from human activities pose a significant risk to ecosystems and human health. Small airborne particles with a diameter of less than 10 microns can be inhaled and then absorbed into the alveolar tissue of the lungs, resulting in damage.