How long should researchers wash their hands with soap and water after handling biohazards, removing ppe and clothing, and before leaving the laboratory?

20-30 seconds

Explanation:

Hand washing is an important activity performed to remove the dirt, soil and other microorganism which gets attached to the hands while doing activities. So the handwashing action is mandatory after the lab experiments to prevent the spread of the microbes and reduce the effects of biohazards.

The hand must be washed after leaving the work area, coming in contact with the infection risk material and removing the personal protective equipment.

The hands must be washed for about 20-30 seconds with warm water and soap.

Thus, 20-30 seconds is the correct answer.