New research suggests a closed toilet seat may not be as helpful to block the spread of germs as we once thought.

The invisible spray is never OK. Flushing the toilet with the lid down does not stop the spread of small germs, a study published Thursday in the American Journal of Infection Control found.

When the toilet was flushed with the lid open, the particles spread over a wide area, including 40 cm above the toilet bowl and 15 cm in front of it on the user’s side. When the toilet was ...