For lead abatement, an enclosure method must be what?

The enclosure method for lead abatement requires a rigid and mechanically attached structure primarily to ensure that the containment of lead-based materials is effective and reliable. Rigid enclosures are designed to withstand physical disturbances and environmental factors, minimizing the risk of lead dust or chips escaping into the surrounding environment.

Additionally, mechanical attachment to the underlying structure ensures that the enclosure remains securely in place over time, preventing any accidental detachment that could lead to exposure risks. This method is essential for maintaining a safe environment during the lead abatement process, as it helps to isolate and contain the hazardous materials being worked with.

The other choices suggest characteristics that are not conducive to effective lead abatement. For instance, flexibility and movability might compromise the containment, while being lightweight and easy to install could imply insufficient structural integrity. Lastly, being secure and easy to remove does not align with the objective of providing long-term protection and stability during lead removal operations.