Is there evidence that shows stairs with open risers are less safe than those with risers

1. What is the difference between an open and closed riser stair?
2. Do stairs have to have risers?

What is the difference between an open and closed riser stair?

Unlike closed riser stairs, the gap between each step in an open riser staircase is open rather than enclosed, allowing you to see underneath or in between the steps. This is the reason why open riser stairs are sometimes called floating stairs.

Do stairs have to have risers?

The ADA states that all stairs and stairway must have uniform riser heights and tread widths. One section also states that stair treads cannot project past the stair riser by more than 1/2″ and should be curved or beveled to help prevent falls from a step.