A bio-coolant was a device that contained a spray that could be used to destroy germ pathogens. Sarah Jane Smith had a bio-coolant inside her attic at 13 Bannerman Road. It looked like a white fire extinguisher.
In 2010 a meteor was falling to Earth. It had a strong possibility of containing germ pathogens. Sarah Jane wanted to destroy it using a bio-coolant. However, when she asked Rani Chandra to use the bio-coolant, Ruby White had already used her own bio coolant spray on the meteor and destroyed the germs that it contained. (TV: Goodbye, Sarah Jane Smith)